diff --git a/CHANGELOG.md b/CHANGELOG.md
index 74832a8e..f961a697 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -1,6 +1,7 @@
 
 # CheckStyle-IDEA Changelog
 
+* **5.99.0** New: Added option to group results by package (#3).
 * **5.98.0** New: Added Checkstyle 10.20.1.
 * **5.97.0** Fixed: Refactored code to fix exception around API dependencies at initialisation (#655).
 * **5.97.0** New: Added Checkstyle 10.19.0.
diff --git a/build.gradle.kts b/build.gradle.kts
index b653d552..992243e5 100644
--- a/build.gradle.kts
+++ b/build.gradle.kts
@@ -19,7 +19,7 @@ plugins {
     id("org.infernus.idea.checkstyle.build")
 }
 
-version = "5.98.0"
+version = "5.99.0"
 
 intellijPlatform {
     pluginConfiguration {
diff --git a/buildSrc/src/main/java/org/infernus/idea/checkstyle/build/GradlePluginMain.java b/buildSrc/src/main/java/org/infernus/idea/checkstyle/build/GradlePluginMain.java
index 3d5f5022..f913cf35 100644
--- a/buildSrc/src/main/java/org/infernus/idea/checkstyle/build/GradlePluginMain.java
+++ b/buildSrc/src/main/java/org/infernus/idea/checkstyle/build/GradlePluginMain.java
@@ -21,8 +21,6 @@
 import org.gradle.language.base.plugins.LifecycleBasePlugin;
 import org.jetbrains.annotations.NotNull;
 
-import static org.codehaus.groovy.runtime.DefaultGroovyMethods.println;
-
 /**
  * The main plugin class. The action starts here.
  */
diff --git a/src/main/java/org/infernus/idea/checkstyle/actions/GroupByFile.java b/src/main/java/org/infernus/idea/checkstyle/actions/GroupByFile.java
new file mode 100644
index 00000000..51735b3c
--- /dev/null
+++ b/src/main/java/org/infernus/idea/checkstyle/actions/GroupByFile.java
@@ -0,0 +1,10 @@
+package org.infernus.idea.checkstyle.actions;
+
+import org.infernus.idea.checkstyle.toolwindow.ResultGrouping;
+
+public class GroupByFile extends GroupingAction {
+
+    public GroupByFile() {
+        super(ResultGrouping.BY_FILE);
+    }
+}
diff --git a/src/main/java/org/infernus/idea/checkstyle/actions/GroupByPackage.java b/src/main/java/org/infernus/idea/checkstyle/actions/GroupByPackage.java
new file mode 100644
index 00000000..c4ed37d0
--- /dev/null
+++ b/src/main/java/org/infernus/idea/checkstyle/actions/GroupByPackage.java
@@ -0,0 +1,10 @@
+package org.infernus.idea.checkstyle.actions;
+
+import org.infernus.idea.checkstyle.toolwindow.ResultGrouping;
+
+public class GroupByPackage extends GroupingAction {
+
+    public GroupByPackage() {
+        super(ResultGrouping.BY_PACKAGE);
+    }
+}
diff --git a/src/main/java/org/infernus/idea/checkstyle/actions/GroupingAction.java b/src/main/java/org/infernus/idea/checkstyle/actions/GroupingAction.java
new file mode 100644
index 00000000..6f63290a
--- /dev/null
+++ b/src/main/java/org/infernus/idea/checkstyle/actions/GroupingAction.java
@@ -0,0 +1,49 @@
+package org.infernus.idea.checkstyle.actions;
+
+import com.intellij.openapi.actionSystem.ActionUpdateThread;
+import com.intellij.openapi.actionSystem.AnActionEvent;
+import com.intellij.openapi.project.DumbAwareToggleAction;
+import com.intellij.openapi.project.Project;
+import org.infernus.idea.checkstyle.toolwindow.ResultGrouping;
+import org.jetbrains.annotations.NotNull;
+
+import java.util.Objects;
+
+import static org.infernus.idea.checkstyle.actions.ToolWindowAccess.*;
+
+abstract class GroupingAction extends DumbAwareToggleAction {
+
+    private final ResultGrouping grouping;
+
+    GroupingAction(@NotNull final ResultGrouping grouping) {
+        this.grouping = grouping;
+    }
+
+    @Override
+    public boolean isSelected(final @NotNull AnActionEvent event) {
+        final Project project = getEventProject(event);
+        if (project == null) {
+            return false;
+        }
+
+        Boolean selected = getFromToolWindowPanel(toolWindow(project), panel -> panel.groupedBy() == grouping);
+        return Objects.requireNonNullElse(selected, false);
+    }
+
+    @Override
+    public void setSelected(final @NotNull AnActionEvent event, final boolean selected) {
+        final Project project = getEventProject(event);
+        if (project == null) {
+            return;
+        }
+
+        actOnToolWindowPanel(toolWindow(project), panel -> {
+            panel.groupBy(grouping);
+        });
+    }
+
+    @Override
+    public @NotNull ActionUpdateThread getActionUpdateThread() {
+        return ActionUpdateThread.EDT;
+    }
+}
diff --git a/src/main/java/org/infernus/idea/checkstyle/toolwindow/CheckStyleToolWindowPanel.java b/src/main/java/org/infernus/idea/checkstyle/toolwindow/CheckStyleToolWindowPanel.java
index 2b5a9e4f..dd415084 100644
--- a/src/main/java/org/infernus/idea/checkstyle/toolwindow/CheckStyleToolWindowPanel.java
+++ b/src/main/java/org/infernus/idea/checkstyle/toolwindow/CheckStyleToolWindowPanel.java
@@ -40,10 +40,8 @@
 import javax.swing.tree.TreePath;
 import java.awt.*;
 import java.awt.event.*;
-import java.util.ArrayList;
-import java.util.HashMap;
+import java.util.*;
 import java.util.List;
-import java.util.Map;
 import java.util.regex.Matcher;
 import java.util.regex.Pattern;
 
@@ -297,7 +295,7 @@ private void clearProgress() {
      */
     private void scrollToError(final TreePath treePath) {
         final DefaultMutableTreeNode treeNode = (DefaultMutableTreeNode) treePath.getLastPathComponent();
-        if (treeNode == null || !(treeNode.getUserObject() instanceof ProblemResultTreeNode nodeInfo)) {
+        if (treeNode == null || !(treeNode.getUserObject() instanceof ProblemResultTreeInfo nodeInfo)) {
             return;
         }
 
@@ -326,11 +324,11 @@ private void scrollToError(final TreePath treePath) {
         }, ModalityState.NON_MODAL);
     }
 
-    private int lineFor(final ProblemResultTreeNode nodeInfo) {
+    private int lineFor(final ProblemResultTreeInfo nodeInfo) {
         return nodeInfo.getProblem().line();
     }
 
-    private int columnFor(final ProblemResultTreeNode nodeInfo) {
+    private int columnFor(final ProblemResultTreeInfo nodeInfo) {
         return nodeInfo.getProblem().column();
     }
 
@@ -521,8 +519,8 @@ public void displayErrorResult(final Throwable error) {
         clearProgress();
     }
 
-    private SeverityLevel[] getDisplayedSeverities() {
-        final List<SeverityLevel> severityLevels = new ArrayList<>();
+    private Set<SeverityLevel> getDisplayedSeverities() {
+        final var severityLevels = new HashSet<SeverityLevel>();
 
         if (displayingErrors) {
             severityLevels.add(SeverityLevel.Error);
@@ -536,7 +534,7 @@ private SeverityLevel[] getDisplayedSeverities() {
             severityLevels.add(SeverityLevel.Info);
         }
 
-        return severityLevels.toArray(new SeverityLevel[0]);
+        return severityLevels;
     }
 
     /**
@@ -586,6 +584,14 @@ public void setDisplayingInfo(final boolean displayingInfo) {
         this.displayingInfo = displayingInfo;
     }
 
+    public void groupBy(final ResultGrouping grouping) {
+        treeModel.groupBy(grouping);
+    }
+
+    public ResultGrouping groupedBy() {
+        return treeModel.groupedBy();
+    }
+
     private PluginConfigurationManager configurationManager() {
         return project.getService(PluginConfigurationManager.class);
     }
diff --git a/src/main/java/org/infernus/idea/checkstyle/toolwindow/FileResultTreeNode.java b/src/main/java/org/infernus/idea/checkstyle/toolwindow/FileResultTreeInfo.java
similarity index 91%
rename from src/main/java/org/infernus/idea/checkstyle/toolwindow/FileResultTreeNode.java
rename to src/main/java/org/infernus/idea/checkstyle/toolwindow/FileResultTreeInfo.java
index 88a00b75..12fc0e53 100644
--- a/src/main/java/org/infernus/idea/checkstyle/toolwindow/FileResultTreeNode.java
+++ b/src/main/java/org/infernus/idea/checkstyle/toolwindow/FileResultTreeInfo.java
@@ -3,7 +3,7 @@
 import com.intellij.icons.AllIcons;
 import org.infernus.idea.checkstyle.CheckStyleBundle;
 
-public class FileResultTreeNode extends ResultTreeNode {
+public class FileResultTreeInfo extends ResultTreeNode {
 
     private final String fileName;
     private final int totalProblems;
@@ -15,7 +15,7 @@ public class FileResultTreeNode extends ResultTreeNode {
      * @param fileName     the name of the file.
      * @param problemCount the number of problems in the file.
      */
-    public FileResultTreeNode(final String fileName, final int problemCount) {
+    public FileResultTreeInfo(final String fileName, final int problemCount) {
         super(CheckStyleBundle.message("plugin.results.scan-file-result", fileName, problemCount));
 
         if (fileName == null) {
diff --git a/src/main/java/org/infernus/idea/checkstyle/toolwindow/PackageTreeInfo.java b/src/main/java/org/infernus/idea/checkstyle/toolwindow/PackageTreeInfo.java
new file mode 100644
index 00000000..fa411460
--- /dev/null
+++ b/src/main/java/org/infernus/idea/checkstyle/toolwindow/PackageTreeInfo.java
@@ -0,0 +1,47 @@
+package org.infernus.idea.checkstyle.toolwindow;
+
+import com.intellij.icons.AllIcons;
+import org.infernus.idea.checkstyle.CheckStyleBundle;
+
+public class PackageTreeInfo extends ResultTreeNode {
+
+    private final String packageName;
+    private final int totalProblems;
+    private int visibleProblems;
+
+    /**
+     * Construct a package node.
+     *
+     * @param packageName     the name of the package.
+     * @param problemCount the number of problems in the file.
+     */
+    public PackageTreeInfo(final String packageName, final int problemCount) {
+        super(CheckStyleBundle.message("plugin.results.scan-file-result", packageName, problemCount));
+
+        if (packageName == null) {
+            throw new IllegalArgumentException("Package name may not be null");
+        }
+
+        this.packageName = packageName;
+        this.totalProblems = problemCount;
+        this.visibleProblems = problemCount;
+
+        updateDisplayText();
+
+        setIcon(AllIcons.Nodes.Package);
+    }
+
+    private void updateDisplayText() {
+        if (totalProblems == visibleProblems) {
+            setText(CheckStyleBundle.message("plugin.results.scan-package-result", packageName, totalProblems));
+        } else {
+            setText(CheckStyleBundle.message("plugin.results.scan-package-result.filtered", packageName, visibleProblems, totalProblems - visibleProblems));
+        }
+    }
+
+    void setVisibleProblems(final int visibleProblems) {
+        this.visibleProblems = visibleProblems;
+
+        updateDisplayText();
+    }
+}
diff --git a/src/main/java/org/infernus/idea/checkstyle/toolwindow/ProblemResultTreeNode.java b/src/main/java/org/infernus/idea/checkstyle/toolwindow/ProblemResultTreeInfo.java
similarity index 94%
rename from src/main/java/org/infernus/idea/checkstyle/toolwindow/ProblemResultTreeNode.java
rename to src/main/java/org/infernus/idea/checkstyle/toolwindow/ProblemResultTreeInfo.java
index c6a34b64..6439d8b5 100644
--- a/src/main/java/org/infernus/idea/checkstyle/toolwindow/ProblemResultTreeNode.java
+++ b/src/main/java/org/infernus/idea/checkstyle/toolwindow/ProblemResultTreeInfo.java
@@ -7,7 +7,7 @@
 import org.infernus.idea.checkstyle.csapi.SeverityLevel;
 import org.jetbrains.annotations.NotNull;
 
-public class ProblemResultTreeNode extends ResultTreeNode {
+public class ProblemResultTreeInfo extends ResultTreeNode {
 
     private final PsiFile file;
     private final Problem problem;
@@ -19,7 +19,7 @@ public class ProblemResultTreeNode extends ResultTreeNode {
      * @param file    the file the problem exists in.
      * @param problem the problem.
      */
-    public ProblemResultTreeNode(@NotNull final PsiFile file,
+    public ProblemResultTreeInfo(@NotNull final PsiFile file,
                                  @NotNull final Problem problem) {
         super(CheckStyleBundle.message("plugin.results.file-result",
                 file.getName(),
diff --git a/src/main/java/org/infernus/idea/checkstyle/toolwindow/ResultGrouping.java b/src/main/java/org/infernus/idea/checkstyle/toolwindow/ResultGrouping.java
new file mode 100644
index 00000000..1f9912f6
--- /dev/null
+++ b/src/main/java/org/infernus/idea/checkstyle/toolwindow/ResultGrouping.java
@@ -0,0 +1,8 @@
+package org.infernus.idea.checkstyle.toolwindow;
+
+public enum ResultGrouping {
+
+    BY_FILE,
+    BY_PACKAGE
+
+}
diff --git a/src/main/java/org/infernus/idea/checkstyle/toolwindow/ResultTreeModel.java b/src/main/java/org/infernus/idea/checkstyle/toolwindow/ResultTreeModel.java
index b1fc127b..f245c5a5 100644
--- a/src/main/java/org/infernus/idea/checkstyle/toolwindow/ResultTreeModel.java
+++ b/src/main/java/org/infernus/idea/checkstyle/toolwindow/ResultTreeModel.java
@@ -8,20 +8,28 @@
 
 import com.intellij.psi.PsiFile;
 import com.intellij.psi.PsiFileSystemItem;
+import com.intellij.psi.PsiJavaFile;
 import org.infernus.idea.checkstyle.CheckStyleBundle;
 import org.infernus.idea.checkstyle.checker.Problem;
 import org.infernus.idea.checkstyle.csapi.SeverityLevel;
+import org.jetbrains.annotations.NotNull;
 import org.jetbrains.annotations.Nullable;
 
+import static java.util.Collections.emptyList;
 import static java.util.Comparator.*;
 
 public class ResultTreeModel extends DefaultTreeModel {
 
     @Serial
     private static final long serialVersionUID = 2161855162879365203L;
+    public static final Set<SeverityLevel> DEFAULT_SEVERITIES = Set.of(SeverityLevel.Error, SeverityLevel.Warning, SeverityLevel.Info);
 
     private final ToggleableTreeNode visibleRootNode;
 
+    private Set<SeverityLevel> displayedSeverities = DEFAULT_SEVERITIES;
+    private ResultGrouping grouping = ResultGrouping.BY_FILE;
+    private Map<PsiFile, List<Problem>> lastResults;
+
     public ResultTreeModel() {
         super(new DefaultMutableTreeNode());
 
@@ -67,66 +75,71 @@ public void setRootMessage(@Nullable final String messageKey,
                                @Nullable final Object... messageArgs) {
         if (messageKey == null) {
             setRootText(null);
-
         } else {
             setRootText(CheckStyleBundle.message(messageKey, messageArgs));
         }
     }
 
+    private void rebuildTree() {
+        visibleRootNode.removeAllChildren();
+
+        switch (grouping) {
+            case BY_FILE -> groupResultsByFile();
+            case BY_PACKAGE -> groupResultsByPackage();
+        }
+
+        filterDisplayedTree();
+        nodeStructureChanged(visibleRootNode);
+    }
+
     /**
      * Display only the passed severity levels.
      *
-     * @param levels the levels. Null is treated as 'none'.
+     * @param severityLevels the levels. An empty set is treated as 'none'.
      */
-    public void filter(final SeverityLevel... levels) {
-        filter(true, levels);
+    public void filter(@NotNull final Set<SeverityLevel> severityLevels) {
+        this.displayedSeverities = severityLevels;
+
+        filterDisplayedTree();
+        nodeStructureChanged(visibleRootNode);
     }
 
-    private void filter(final boolean sendEvents, final SeverityLevel... levels) {
-        for (final ToggleableTreeNode fileNode : visibleRootNode.getAllChildren()) {
-            for (final ToggleableTreeNode problemNode : fileNode.getAllChildren()) {
-                final ProblemResultTreeNode result = (ProblemResultTreeNode) problemNode.getUserObject();
+    public void groupBy(@NotNull final ResultGrouping resultGrouping) {
+        this.grouping = resultGrouping;
 
-                final boolean resultShouldBeVisible = contains(levels, result.getSeverity());
-                if (problemNode.isVisible() != resultShouldBeVisible) {
-                    problemNode.setVisible(resultShouldBeVisible);
-                }
-            }
+        rebuildTree();
+    }
 
-            ((FileResultTreeNode) fileNode.getUserObject()).setVisibleProblems(fileNode.getChildCount());
-            final boolean fileNodeShouldBeVisible = fileNode.getChildCount() > 0;
-            if (fileNode.isVisible() != fileNodeShouldBeVisible) {
-                fileNode.setVisible(fileNodeShouldBeVisible);
-            }
-        }
+    public ResultGrouping groupedBy() {
+        return grouping;
+    }
 
-        if (sendEvents) {
-            nodeStructureChanged(visibleRootNode);
-        }
+    private void filterDisplayedTree() {
+        filterNodeAndChildren(visibleRootNode);
     }
 
-    /*
-     * This is a port from commons-lang 2.4, in order to get around the absence of commons-lang in
-     * some packages of IDEA 7.x.
-     */
-    private boolean contains(final Object[] array, final Object objectToFind) {
-        if (array == null) {
-            return false;
+    private void filterNodeAndChildren(final ToggleableTreeNode node) {
+        boolean nodeShouldBeVisible = true;
+
+        for (final var childNode : node.getAllChildren()) {
+            filterNodeAndChildren(childNode);
         }
-        if (objectToFind == null) {
-            for (final Object anArray : array) {
-                if (anArray == null) {
-                    return true;
-                }
-            }
-        } else {
-            for (final Object anArray : array) {
-                if (objectToFind.equals(anArray)) {
-                    return true;
-                }
-            }
+
+        if (node.getUserObject() instanceof FileResultTreeInfo fileResultTreeInfo) {
+            fileResultTreeInfo.setVisibleProblems(node.getChildCount());
+            nodeShouldBeVisible = node.getChildCount() > 0;
+
+        } else if (node.getUserObject() instanceof PackageTreeInfo packageTreeInfo) {
+            packageTreeInfo.setVisibleProblems(node.getChildCount());
+            nodeShouldBeVisible = node.getChildCount() > 0;
+
+        } else if (node.getUserObject() instanceof ProblemResultTreeInfo problemResultTreeInfo) {
+            nodeShouldBeVisible = displayedSeverities.contains(problemResultTreeInfo.getSeverity());
+        }
+
+        if (node.isVisible() != nodeShouldBeVisible) {
+            node.setVisible(nodeShouldBeVisible);
         }
-        return false;
     }
 
     /**
@@ -134,8 +147,8 @@ private boolean contains(final Object[] array, final Object objectToFind) {
      *
      * @param results the model.
      */
-    public void setModel(final Map<PsiFile, List<Problem>> results) {
-        setModel(results, SeverityLevel.Error, SeverityLevel.Warning, SeverityLevel.Info);
+    public void setModel(@NotNull  final Map<PsiFile, List<Problem>> results) {
+        setModel(results, DEFAULT_SEVERITIES);
     }
 
     /**
@@ -144,55 +157,101 @@ public void setModel(final Map<PsiFile, List<Problem>> results) {
      * @param results the model.
      * @param levels  the levels to display.
      */
-    public void setModel(final Map<PsiFile, List<Problem>> results,
-                         final SeverityLevel... levels) {
-        visibleRootNode.removeAllChildren();
+    public void setModel(@NotNull final Map<PsiFile, List<Problem>> results,
+                         @NotNull final Set<SeverityLevel> levels) {
+        this.lastResults = results;
+        this.displayedSeverities = levels;
+
+        rebuildTree();
+    }
 
-        int itemCount = 0;
-        for (final PsiFile file : sortedFileNames(results)) {
-            final ToggleableTreeNode fileNode = new ToggleableTreeNode();
-            final List<Problem> problems = results.get(file);
+    private void groupResultsByFile() {
+        int problemCount = createFileNodes(sortByFileName(lastResults), visibleRootNode);
+        setRootMessage(problemCount);
+    }
 
-            int problemCount = 0;
-            if (problems != null) {
-                for (final Problem problem : problems) {
-                    if (problem.severityLevel() != SeverityLevel.Ignore) {
-                        final ResultTreeNode problemObj = new ProblemResultTreeNode(file, problem);
+    private List<PsiFile> sortByFileName(final Map<PsiFile, List<Problem>> results) {
+        if (results == null || results.isEmpty()) {
+            return emptyList();
+        }
+        var sortedFiles = new ArrayList<>(results.keySet());
+        sortedFiles.sort(comparing(PsiFileSystemItem::getName));
+        return sortedFiles;
+    }
 
-                        final ToggleableTreeNode problemNode = new ToggleableTreeNode(problemObj);
-                        fileNode.add(problemNode);
+    private void groupResultsByPackage() {
+        int problemCount = 0;
 
-                        ++problemCount;
-                    }
-                }
+        var groupedByPackage = groupByPackageName(lastResults);
+        for (String packageName : groupedByPackage.keySet()) {
+            final var packageNode = new ToggleableTreeNode();
+
+            var childProblemCount = createFileNodes(groupedByPackage.getOrDefault(packageName, emptyList()), packageNode);
+            if (childProblemCount > 0) {
+                final var packageInfo = new PackageTreeInfo(packageName, childProblemCount);
+                packageNode.setUserObject(packageInfo);
+                visibleRootNode.add(packageNode);
             }
 
-            itemCount += problemCount;
+            problemCount += childProblemCount;
+        }
+
+        setRootMessage(problemCount);
+    }
+
+    private int createFileNodes(final List<PsiFile> files,
+                                final ToggleableTreeNode parentNode) {
+        int problemCount = 0;
+        for (final PsiFile file : files) {
+            final var fileNode = new ToggleableTreeNode();
+            final var problems = lastResults.getOrDefault(file, emptyList());
+
+            int childProblemCount = 0;
+            for (final Problem problem : problems) {
+                if (problem.severityLevel() != SeverityLevel.Ignore) {
+                    final var problemInfo = new ProblemResultTreeInfo(file, problem);
+                    fileNode.add(new ToggleableTreeNode(problemInfo));
+
+                    ++childProblemCount;
+                }
+            }
 
-            if (problemCount > 0) {
-                final ResultTreeNode nodeObject = new FileResultTreeNode(file.getName(), problemCount);
+            if (childProblemCount > 0) {
+                var nodeObject = new FileResultTreeInfo(file.getName(), childProblemCount);
                 fileNode.setUserObject(nodeObject);
 
-                visibleRootNode.add(fileNode);
+                parentNode.add(fileNode);
             }
-        }
 
-        if (itemCount == 0) {
-            setRootMessage("plugin.results.scan-no-results");
-        } else {
-            setRootText(CheckStyleBundle.message("plugin.results.scan-results", itemCount, results.size()));
+            problemCount += childProblemCount;
         }
-
-        filter(false, levels);
-        nodeStructureChanged(visibleRootNode);
+        return problemCount;
     }
 
-    private Iterable<PsiFile> sortedFileNames(final Map<PsiFile, List<Problem>> results) {
+    private SortedMap<String, List<PsiFile>> groupByPackageName(final Map<PsiFile, List<Problem>> results) {
         if (results == null || results.isEmpty()) {
-            return Collections.emptyList();
+            return Collections.emptySortedMap();
+        }
+        var groupedByPackage = new TreeMap<String, List<PsiFile>>();
+        for (var result : results.keySet()) {
+            var filePackage = CheckStyleBundle.message("plugin.results.unknown-package");
+            if (result instanceof PsiJavaFile javaFile) {
+                filePackage = javaFile.getPackageName();
+
+                if (filePackage.trim().isEmpty()) {
+                    filePackage = CheckStyleBundle.message("plugin.results.root-package");
+                }
+            }
+            groupedByPackage.computeIfAbsent(filePackage,  key -> new ArrayList<>()).add(result);
+        }
+        return groupedByPackage;
+    }
+
+    private void setRootMessage(final int problemCount) {
+        if (problemCount == 0) {
+            setRootMessage("plugin.results.scan-no-results");
+        } else {
+            setRootText(CheckStyleBundle.message("plugin.results.scan-results", problemCount, lastResults.size()));
         }
-        final List<PsiFile> sortedFiles = new ArrayList<>(results.keySet());
-        sortedFiles.sort(comparing(PsiFileSystemItem::getName));
-        return sortedFiles;
     }
 }
diff --git a/src/main/java/org/infernus/idea/checkstyle/toolwindow/ResultTreeRenderer.java b/src/main/java/org/infernus/idea/checkstyle/toolwindow/ResultTreeRenderer.java
index c538b8cf..866b475e 100644
--- a/src/main/java/org/infernus/idea/checkstyle/toolwindow/ResultTreeRenderer.java
+++ b/src/main/java/org/infernus/idea/checkstyle/toolwindow/ResultTreeRenderer.java
@@ -19,7 +19,6 @@ public class ResultTreeRenderer extends JLabel
      * Create a new cell renderer.
      */
     public ResultTreeRenderer() {
-        super();
         setOpaque(false);
     }
 
diff --git a/src/main/resources/META-INF/plugin.xml b/src/main/resources/META-INF/plugin.xml
index 2ca1e0eb..f3ea3787 100644
--- a/src/main/resources/META-INF/plugin.xml
+++ b/src/main/resources/META-INF/plugin.xml
@@ -25,6 +25,7 @@
     <change-notes>
         <![CDATA[
 <ul>
+    <li>5.99.0: Added option to group results by package (#3).</li>
     <li>5.98.0: New: Added Checkstyle 10.20.1.</li>
     <li>5.97.0: Fixed: Refactored code to fix exception around API dependencies at initialisation (#655).</li>
     <li>5.97.0: New: Added Checkstyle 10.19.0.</li>1
@@ -153,6 +154,20 @@
                     text="Display Information Results"
                     description="Display information results"
                     icon="/general/information.svg"/>
+
+            <separator/>
+
+            <action id="CheckStyleGroupByFileAction"
+                    class="org.infernus.idea.checkstyle.actions.GroupByFile"
+                    text="Group Results By File"
+                    description="Group the displayed results by file"
+                    icon="/actions/GroupByFile.svg"/>
+
+            <action id="CheckStyleGroupByPackageAction"
+                    class="org.infernus.idea.checkstyle.actions.GroupByPackage"
+                    text="Group Results By Package"
+                    description="Group the displayed results by their package"
+                    icon="/actions/GroupByPackage.svg"/>
         </group>
 
         <group id="CheckStylePluginActions" text="CheckStyle" popup="true">
diff --git a/src/main/resources/org/infernus/idea/checkstyle/CheckStyleBundle.properties b/src/main/resources/org/infernus/idea/checkstyle/CheckStyleBundle.properties
index 75cbc899..5af2859d 100644
--- a/src/main/resources/org/infernus/idea/checkstyle/CheckStyleBundle.properties
+++ b/src/main/resources/org/infernus/idea/checkstyle/CheckStyleBundle.properties
@@ -19,10 +19,14 @@ plugin.results.error.instantiation-failed=The module {0} could not be loaded - \
   please check you have added any prerequisites to the classpath
 plugin.results.scan-no-results=Checkstyle found no problems in the file(s)
 plugin.results.scan-results=Checkstyle found {0} item(s) in {1} file(s)
+plugin.results.scan-package-result={0} : {1} item(s)
+plugin.results.scan-package-result.filtered={0} : {1} item(s), {2} more hidden
 plugin.results.scan-file-result={0} : {1} item(s)
 plugin.results.scan-file-result.filtered={0} : {1} item(s), {2} more hidden
 plugin.results.file-result={1} ({2}:{3}) [{4}]
 plugin.results.unknown-source=unknown
+plugin.results.unknown-package=Non-java file
+plugin.results.root-package=<root>
 plugin.status.in-progress.current=Scanning current file...
 plugin.status.in-progress.module=Scanning current module...
 plugin.status.in-progress.no-file=No file is open for editing