diff --git a/src/checks/content-structure/section-header-quality.ts b/src/checks/content-structure/section-header-quality.ts
index 82484ec..816b431 100644
--- a/src/checks/content-structure/section-header-quality.ts
+++ b/src/checks/content-structure/section-header-quality.ts
@@ -1,3 +1,4 @@
+import type { HTMLElement } from 'node-html-parser';
 import { parse } from 'node-html-parser';
 import { registerCheck } from '../registry.js';
 import type { CheckContext, CheckResult, CheckStatus } from '../../types.js';
@@ -23,17 +24,52 @@ interface GroupHeaderAnalysis {
 
 const MD_HEADING_RE = /^#{1,6}\s+(.+)$/gm;
 
+const CALLOUT_ROLES = new Set(['alert', 'note', 'status', 'complementary']);
+
+/**
+ * Check whether a heading is inside a callout/admonition container rather than
+ * being a structural section header. Walks up the ancestor chain looking for
+ * signals: semantic HTML (<aside>), ARIA roles, class names containing
+ * "callout"/"admonition", or data-* attribute values containing those keywords.
+ */
+function isCalloutHeading(h: HTMLElement): boolean {
+  let el: HTMLElement | null = h;
+  while (el) {
+    // Semantic HTML
+    if (el.rawTagName === 'aside') return true;
+
+    // ARIA roles
+    const role = el.getAttribute('role');
+    if (role && CALLOUT_ROLES.has(role)) return true;
+
+    // Class and data-* attribute values
+    const attrs = el.attributes;
+    for (const [key, value] of Object.entries(attrs)) {
+      if (key === 'role') continue; // already checked
+      if (key === 'class' || key.startsWith('data-')) {
+        const lower = value.toLowerCase();
+        if (lower.includes('callout') || lower.includes('admonition')) return true;
+      }
+    }
+
+    el = el.parentNode as HTMLElement | null;
+  }
+  return false;
+}
+
 /**
- * Extract header text from content that may be HTML, markdown, or a mix (MDX).
- * Tries HTML parsing first, then falls back to markdown heading regex.
+ * Extract section header text from content that may be HTML, markdown, or a
+ * mix (MDX). Excludes headings inside callout/admonition containers, which
+ * are supplementary labels rather than structural section headers.
  */
 function extractHeaders(content: string): string[] {
   const headers: string[] = [];
 
-  // HTML headers
+  // HTML headers — skip callout/admonition headings
   const root = parse(content);
   const htmlHeaders = root.querySelectorAll('h1, h2, h3, h4, h5, h6');
   for (const h of htmlHeaders) {
+    if (isCalloutHeading(h)) continue;
     const text = h.textContent.trim();
     if (text.length > 0) headers.push(text);
   }
diff --git a/test/unit/checks/section-header-quality.test.ts b/test/unit/checks/section-header-quality.test.ts
index 535e96e..8f546b9 100644
--- a/test/unit/checks/section-header-quality.test.ts
+++ b/test/unit/checks/section-header-quality.test.ts
@@ -558,6 +558,291 @@ describe('section-header-quality', () => {
     );
   });
 
+  // Callout/admonition heading exclusion tests (issue #51)
+  it('excludes callout headings inside <aside> elements', async () => {
+    const result = await check.run(
+      makeCtx({
+        status: 'pass',
+        tabbedPages: [
+          {
+            url: 'http://test.local/page',
+            tabGroups: [
+              {
+                framework: 'generic-aria',
+                tabCount: 2,
+                htmlSlice: '<div></div>',
+                panels: [
+                  {
+                    label: 'Python',
+                    html: '<div><aside><h2>Warning</h2><p>Be careful</p></aside></div>',
+                  },
+                  {
+                    label: 'Node',
+                    html: '<div><aside><h2>Warning</h2><p>Be careful</p></aside></div>',
+                  },
+                ],
+              },
+            ],
+            totalTabbedChars: 100,
+            status: 'pass',
+          },
+        ],
+      }),
+    );
+    // No section headers remain after excluding callout headings
+    expect(result.status).toBe('skip');
+    expect(result.message).toContain('no section headers inside tab panels');
+  });
+
+  it('excludes callout headings inside elements with ARIA role="note"', async () => {
+    const result = await check.run(
+      makeCtx({
+        status: 'pass',
+        tabbedPages: [
+          {
+            url: 'http://test.local/page',
+            tabGroups: [
+              {
+                framework: 'generic-aria',
+                tabCount: 2,
+                htmlSlice: '<div></div>',
+                panels: [
+                  {
+                    label: 'Python',
+                    html: '<div><div role="note"><h3>Note</h3><p>Info here</p></div></div>',
+                  },
+                  {
+                    label: 'Node',
+                    html: '<div><div role="note"><h3>Note</h3><p>Info here</p></div></div>',
+                  },
+                ],
+              },
+            ],
+            totalTabbedChars: 100,
+            status: 'pass',
+          },
+        ],
+      }),
+    );
+    expect(result.status).toBe('skip');
+    expect(result.message).toContain('no section headers inside tab panels');
+  });
+
+  it('excludes callout headings inside elements with admonition class', async () => {
+    const result = await check.run(
+      makeCtx({
+        status: 'pass',
+        tabbedPages: [
+          {
+            url: 'http://test.local/page',
+            tabGroups: [
+              {
+                framework: 'mkdocs',
+                tabCount: 2,
+                htmlSlice: '<div></div>',
+                panels: [
+                  {
+                    label: 'Python',
+                    html: '<div><div class="admonition warning"><h3>Warning</h3><p>Careful</p></div></div>',
+                  },
+                  {
+                    label: 'Node',
+                    html: '<div><div class="admonition warning"><h3>Warning</h3><p>Careful</p></div></div>',
+                  },
+                ],
+              },
+            ],
+            totalTabbedChars: 100,
+            status: 'pass',
+          },
+        ],
+      }),
+    );
+    expect(result.status).toBe('skip');
+    expect(result.message).toContain('no section headers inside tab panels');
+  });
+
+  it('excludes callout headings inside elements with data-* callout attributes', async () => {
+    // Twilio Paste pattern: data-paste-element="CALLOUT" on ancestor
+    const result = await check.run(
+      makeCtx({
+        status: 'pass',
+        tabbedPages: [
+          {
+            url: 'http://test.local/page',
+            tabGroups: [
+              {
+                framework: 'generic-aria',
+                tabCount: 2,
+                htmlSlice: '<div></div>',
+                panels: [
+                  {
+                    label: 'Python',
+                    html: '<div><div data-paste-element="CALLOUT"><div><h2 data-paste-element="CALLOUT_HEADING">Warning</h2></div></div></div>',
+                  },
+                  {
+                    label: 'Node',
+                    html: '<div><div data-paste-element="CALLOUT"><div><h2 data-paste-element="CALLOUT_HEADING">Warning</h2></div></div></div>',
+                  },
+                ],
+              },
+            ],
+            totalTabbedChars: 100,
+            status: 'pass',
+          },
+        ],
+      }),
+    );
+    expect(result.status).toBe('skip');
+    expect(result.message).toContain('no section headers inside tab panels');
+  });
+
+  it('counts section headers but ignores callout headings in the same panel', async () => {
+    // Panels have both a real section header and a callout heading.
+    // Only the section header should be counted; the callout should be ignored.
+    const result = await check.run(
+      makeCtx({
+        status: 'pass',
+        tabbedPages: [
+          {
+            url: 'http://test.local/page',
+            tabGroups: [
+              {
+                framework: 'generic-aria',
+                tabCount: 2,
+                htmlSlice: '<div></div>',
+                panels: [
+                  {
+                    label: 'Python',
+                    html: '<div><h2>Python Setup</h2><aside><h3>Warning</h3><p>Be careful</p></aside></div>',
+                  },
+                  {
+                    label: 'Node',
+                    html: '<div><h2>Node Setup</h2><aside><h3>Warning</h3><p>Be careful</p></aside></div>',
+                  },
+                ],
+              },
+            ],
+            totalTabbedChars: 100,
+            status: 'pass',
+          },
+        ],
+      }),
+    );
+    // "Python Setup" and "Node Setup" include variant context → pass
+    // "Warning" in <aside> is excluded from analysis entirely
+    expect(result.status).toBe('pass');
+    expect(result.details?.groupsWithGenericMajority).toBe(0);
+  });
+
+  // Framework-specific callout pattern tests
+  it('excludes Bootstrap alert headings (role="alert" + alert-heading)', async () => {
+    const result = await check.run(
+      makeCtx({
+        status: 'pass',
+        tabbedPages: [
+          {
+            url: 'http://test.local/page',
+            tabGroups: [
+              {
+                framework: 'generic-aria',
+                tabCount: 2,
+                htmlSlice: '<div></div>',
+                panels: [
+                  {
+                    label: 'Python',
+                    html: '<div><div class="alert alert-warning" role="alert"><h4 class="alert-heading">Warning!</h4><p>Check your configuration.</p></div></div>',
+                  },
+                  {
+                    label: 'Node',
+                    html: '<div><div class="alert alert-warning" role="alert"><h4 class="alert-heading">Warning!</h4><p>Check your configuration.</p></div></div>',
+                  },
+                ],
+              },
+            ],
+            totalTabbedChars: 100,
+            status: 'pass',
+          },
+        ],
+      }),
+    );
+    expect(result.status).toBe('skip');
+    expect(result.message).toContain('no section headers inside tab panels');
+  });
+
+  it('excludes headings inside Docusaurus admonition containers', async () => {
+    // Docusaurus uses class names containing "admonition" and "alert"
+    const result = await check.run(
+      makeCtx({
+        status: 'pass',
+        tabbedPages: [
+          {
+            url: 'http://test.local/page',
+            tabGroups: [
+              {
+                framework: 'docusaurus',
+                tabCount: 2,
+                htmlSlice: '<div></div>',
+                panels: [
+                  {
+                    label: 'Python',
+                    html: '<div><div class="theme-admonition theme-admonition-warning admonition_xJq3 alert alert--warning"><h5>Deprecation Notice</h5><p>This API will be removed.</p></div></div>',
+                  },
+                  {
+                    label: 'Node',
+                    html: '<div><div class="theme-admonition theme-admonition-warning admonition_xJq3 alert alert--warning"><h5>Deprecation Notice</h5><p>This API will be removed.</p></div></div>',
+                  },
+                ],
+              },
+            ],
+            totalTabbedChars: 100,
+            status: 'pass',
+          },
+        ],
+      }),
+    );
+    expect(result.status).toBe('skip');
+    expect(result.message).toContain('no section headers inside tab panels');
+  });
+
+  it('excludes headings inside Sphinx/MkDocs admonition with nested content', async () => {
+    // Sphinx/MkDocs admonition titles use <p>, but user content inside
+    // the admonition could contain headings (e.g., a long note with sections)
+    const result = await check.run(
+      makeCtx({
+        status: 'pass',
+        tabbedPages: [
+          {
+            url: 'http://test.local/page',
+            tabGroups: [
+              {
+                framework: 'sphinx',
+                tabCount: 2,
+                htmlSlice: '<div></div>',
+                panels: [
+                  {
+                    label: 'Python',
+                    html: '<div><h2>Python Setup</h2><div class="admonition note"><p class="admonition-title">Note</p><h4>Prerequisites</h4><p>You need Python 3.8+</p></div></div>',
+                  },
+                  {
+                    label: 'Node',
+                    html: '<div><h2>Node Setup</h2><div class="admonition note"><p class="admonition-title">Note</p><h4>Prerequisites</h4><p>You need Node 18+</p></div></div>',
+                  },
+                ],
+              },
+            ],
+            totalTabbedChars: 200,
+            status: 'pass',
+          },
+        ],
+      }),
+    );
+    // "Python Setup" / "Node Setup" are section headers → counted, contextual → pass
+    // "Prerequisites" inside .admonition → excluded
+    expect(result.status).toBe('pass');
+    expect(result.details?.groupsWithGenericMajority).toBe(0);
+  });
+
   it('detects contextual markdown headers in MDX panels', async () => {
     const result = await check.run(
       makeCtx({