diff --git a/cypress/e2e/state.cy.ts b/cypress/e2e/state.cy.ts
index 4347bd66..04facc04 100644
--- a/cypress/e2e/state.cy.ts
+++ b/cypress/e2e/state.cy.ts
@@ -19,7 +19,7 @@ describe('State', { testIsolation: false }, () => {
     cy.get('[data-a11y-dialog-show="something-else"]').click()
     cy.get('.dialog').then(shouldBeHidden)
 
-    cy.get('[data-a11y-dialog-show="my-dialog"]').click()
+    cy.get('[data-a11y-dialog-show="my-dialog"]').first().click()
     cy.get('.dialog').then(shouldBeVisible)
   })
 
@@ -28,14 +28,18 @@ describe('State', { testIsolation: false }, () => {
     cy.get('.dialog').then(shouldBeHidden)
   })
 
+  it('should open the dialog when clicking a custom element opener', () => {
+    cy.get('fancy-button').click()
+    cy.get('.dialog').then(shouldBeVisible)
+  })
+
   it('should close when pressing ESC', () => {
-    cy.get('[data-a11y-dialog-show="my-dialog"]').click()
     cy.realPress('Escape')
     cy.get('.dialog').then(shouldBeHidden)
   })
 
   it('should not close when pressing ESC if it contains an open popover', () => {
-    cy.get('[data-a11y-dialog-show="my-dialog"]').click()
+    cy.get('[data-a11y-dialog-show="my-dialog"]').first().click()
     cy.get('[popovertarget]').click()
     cy.get('[popover]').should('be.visible')
     cy.realPress('Escape')
@@ -46,7 +50,7 @@ describe('State', { testIsolation: false }, () => {
   })
 
   it('should close when clicking the backdrop', () => {
-    cy.get('[data-a11y-dialog-show="my-dialog"]').click()
+    cy.get('[data-a11y-dialog-show="my-dialog"]').first().click()
     cy.get('.dialog-overlay').click({ force: true })
     cy.get('.dialog').then(shouldBeHidden)
   })
@@ -56,7 +60,7 @@ describe('State', { testIsolation: false }, () => {
       $node[0].addEventListener('show', cy.stub().as('shown'))
       $node[0].addEventListener('hide', cy.stub().as('hidden'))
     })
-    cy.get('[data-a11y-dialog-show="my-dialog"]').click()
+    cy.get('[data-a11y-dialog-show="my-dialog"]').first().click()
     cy.get('@shown').should('have.been.calledOnce')
     cy.get('.dialog-overlay').click({ force: true })
     cy.get('@hidden').should('have.been.calledOnce')
diff --git a/cypress/e2e/utils.ts b/cypress/e2e/utils.ts
index e6be41a8..239a718f 100644
--- a/cypress/e2e/utils.ts
+++ b/cypress/e2e/utils.ts
@@ -6,8 +6,14 @@ export function shouldBeVisible($subject: Parameters<(typeof cy)['wrap']>[0]) {
     consoleProps: () => ({ $el: $subject }),
   })
 
-  cy.wrap($subject, { log: false }).should('not.have.attr', 'aria-hidden')
-  cy.wrap($subject, { log: false })
+  if ($subject[0].shadowRoot) {
+    cy.wrap($subject, { log: false }).shadow().find('.dialog').as('subject')
+  } else {
+    cy.wrap($subject, { log: false }).as('subject')
+  }
+
+  cy.get('@subject').should('not.have.attr', 'aria-hidden')
+  cy.get('@subject')
     .find('.dialog-content', { log: false })
     .should('be.visible')
 }
@@ -20,11 +26,17 @@ export function shouldBeHidden($subject: Parameters<(typeof cy)['wrap']>[0]) {
     consoleProps: () => ({ $el: $subject }),
   })
 
-  cy.wrap($subject, { log: false })
-    .should('have.attr', 'aria-hidden', 'true')
+  if ($subject[0].shadowRoot) {
+    cy.wrap($subject, { log: false }).shadow().find('.dialog').as('subject')
+  } else {
+    cy.wrap($subject, { log: false }).as('subject')
+  }
+
+  cy.get('@subject').should('have.attr', 'aria-hidden', 'true')
+  cy.get('@subject')
     .find('.dialog-overlay', { log: false })
     .should('not.be.visible')
-  cy.wrap($subject, { log: false })
+  cy.get('@subject')
     .find('.dialog-content', { log: false })
     .should('not.be.visible')
 }
diff --git a/cypress/e2e/webComponents.cy.ts b/cypress/e2e/webComponents.cy.ts
new file mode 100644
index 00000000..a07fb7ee
--- /dev/null
+++ b/cypress/e2e/webComponents.cy.ts
@@ -0,0 +1,61 @@
+import { shouldBeHidden, shouldBeVisible } from './utils.ts'
+
+describe('Web Components', () => {
+  beforeEach(() => cy.visit('/web-components'))
+
+  it('should focus the dialog container on open', () => {
+    cy.get('my-dialog').shadow().find('[data-show]').first().click()
+    cy.get('my-dialog').then(shouldBeVisible)
+    cy.get('my-dialog').should('have.focus')
+  })
+
+  it('should close with ESC', () => {
+    cy.get('my-dialog').shadow().find('[data-show]').first().click()
+    cy.realPress('Escape')
+    cy.get('my-dialog').then(shouldBeHidden)
+  })
+
+  it('should close with close button', () => {
+    cy.get('my-dialog').shadow().find('[data-show]').first().click()
+    cy.get('my-dialog').shadow().find('.dialog-close').click()
+    cy.get('my-dialog').then(shouldBeHidden)
+  })
+
+  it('should restore focus to the previously focused element', () => {
+    cy.get('my-dialog').shadow().find('[data-show]').first().click()
+    cy.get('my-dialog').shadow().find('.dialog-close').click()
+    cy.get('my-dialog')
+      .shadow()
+      .find('[data-show]')
+      .first()
+      .should('have.focus')
+  })
+
+  it('should handle opening and closing with a custom element', () => {
+    // In a custom element, the event target ends up being the shadow root which
+    // is the custom dialog element in this instance
+    const handlers = {
+      show: event => {
+        expect(event.detail.target.tagName).to.eq('MY-DIALOG')
+        expect(event.detail.composedPath()[0].tagName).to.eq('FANCY-BUTTON')
+      },
+      hide: event => {
+        expect(event.detail.target.tagName).to.eq('MY-DIALOG')
+        expect(event.detail.composedPath()[0].tagName).to.eq('FANCY-BUTTON')
+      },
+    }
+
+    cy.spy(handlers, 'show').as('show')
+    cy.spy(handlers, 'hide').as('hide')
+    cy.window().its('instance').invoke('on', 'show', handlers.show)
+    cy.window().its('instance').invoke('on', 'hide', handlers.hide)
+    cy.get('my-dialog').shadow().find('fancy-button').first().click()
+    cy.get('@show').should('have.been.called')
+    cy.get('my-dialog').then(shouldBeVisible)
+    cy.get('my-dialog').shadow().find('fancy-button').last().click()
+    cy.get('@hide').should('have.been.called')
+    cy.get('my-dialog').then(shouldBeHidden)
+    cy.window().its('instance').invoke('off', 'show', handlers.show)
+    cy.window().its('instance').invoke('off', 'hide', handlers.hide)
+  })
+})
diff --git a/cypress/fixtures/base.html b/cypress/fixtures/base.html
index 6701f532..d4efb823 100644
--- a/cypress/fixtures/base.html
+++ b/cypress/fixtures/base.html
@@ -12,6 +12,7 @@
     <h1>Tests — Base</h1>
     <button class="link-like" data-a11y-dialog-show="my-dialog">Open the dialog window</button>
     <button class="link-like" data-a11y-dialog-show="something-else">Open the dialog window</button>
+    <fancy-button class="link-like" data-a11y-dialog-show="my-dialog">Open the dialog window</fancy-button>
   </main>
 
   <div class="dialog" data-a11y-dialog="my-dialog" aria-labelledby="my-dialog-title">
@@ -42,6 +43,7 @@ <h1 id="my-dialog-title">Dialog title</h1>
   </div>
 
   <script src="./a11y-dialog.js"></script>
+  <script src="./shadow-dom-fixture.js"></script>
   <script>
     document.querySelector('#move-focus-outside').addEventListener('click', () => {
       document.querySelector('#focus-me').focus()
@@ -49,4 +51,4 @@ <h1 id="my-dialog-title">Dialog title</h1>
   </script>
 </body>
 
-</html>
+</html>
\ No newline at end of file
diff --git a/cypress/fixtures/web-components.html b/cypress/fixtures/web-components.html
new file mode 100644
index 00000000..029b625d
--- /dev/null
+++ b/cypress/fixtures/web-components.html
@@ -0,0 +1,57 @@
+<!doctype html>
+<html lang="en">
+
+<head>
+  <meta charset="utf-8">
+  <title>Tests — Web Components</title>
+  <link rel="stylesheet" href="../styles.css" />
+</head>
+
+<body>
+  <main>
+    <h1>Tests — Web Components</h1>
+
+    <my-dialog>
+      <template>
+        <button type="button" data-show>Open the dialog</button>
+        <fancy-button data-a11y-dialog-show="my-dialog">
+          Open the dialog
+        </fancy-button>
+        <div class="dialog" id="my-dialog" aria-labelledby="my-dialog-title" aria-hidden="true">
+          <div class="dialog-overlay" data-a11y-dialog-hide></div>
+          <div class="dialog-content" role="document">
+            <button data-a11y-dialog-hide class="dialog-close" aria-label="Close this dialog window">&times;</button>
+            <fancy-button data-a11y-dialog-hide>
+              Close the dialog
+            </fancy-button>
+            <h1 id="my-dialog-title">Your dialog title</h1>
+          </div>
+        </div>
+        <link rel="stylesheet" href="../styles.css" />
+      </template>
+    </my-dialog>
+  </main>
+
+  <script src="./a11y-dialog.js"></script>
+  <script src="./shadow-dom-fixture.js"></script>
+  <script>
+    class MyDialog extends HTMLElement {
+      connectedCallback() {
+        const shadow = this.attachShadow({ mode: 'open' });
+        const template = this.querySelector('template');
+        shadow.appendChild(template.content.cloneNode(true));
+
+        const container = this.shadowRoot.querySelector("#my-dialog");
+        const dialog = new A11yDialog(container);
+        window.instance = dialog
+
+        const triggers = this.shadowRoot.querySelectorAll('[data-show]');
+        triggers.forEach(trigger => trigger.addEventListener('click', (event) => dialog.show(event)))
+      }
+    }
+
+    customElements.define("my-dialog", MyDialog);
+  </script>
+</body>
+
+</html>
\ No newline at end of file
diff --git a/src/a11y-dialog.ts b/src/a11y-dialog.ts
index 4dde431e..2e21e68c 100644
--- a/src/a11y-dialog.ts
+++ b/src/a11y-dialog.ts
@@ -186,7 +186,12 @@ export default class A11yDialog {
    * dialog are clicked, and call `show` or `hide`, respectively
    */
   private handleTriggerClicks(event: Event) {
-    const target = event.target as HTMLElement
+    // We need to retrieve the click target while accounting for Shadow DOM.
+    // When within a web component, `event.target` is the shadow root (e.g.
+    // `<my-dialog>`), so we need to use `event.composedPath()` to get the click
+    // target
+    // See: https://github.com/KittyGiraudel/a11y-dialog/issues/582
+    const target = event.composedPath()[0] as HTMLElement
 
     // We use `.closest(..)` and not `.matches(..)` here so that clicking
     // an element nested within a dialog opener does cause the dialog to open