diff --git a/packages/core/src/components/accordion/accordion-content.tsx b/packages/core/src/components/accordion/accordion-content.tsx
new file mode 100644
index 0000000..da019a1
--- /dev/null
+++ b/packages/core/src/components/accordion/accordion-content.tsx
@@ -0,0 +1,29 @@
+import type { JSX } from "solid-js";
+import { splitProps } from "solid-js";
+import { useAccordionItemContext } from "./accordion-context";
+
+export interface AccordionContentProps extends JSX.HTMLAttributes<HTMLDivElement> {
+  children?: JSX.Element;
+}
+
+/**
+ * Content panel for an Accordion item. Stays in DOM (uses hidden attribute)
+ * so CSS transitions work when animating open/closed.
+ */
+export function AccordionContent(props: AccordionContentProps): JSX.Element {
+  const [local, rest] = splitProps(props, ["children"]);
+  const itemCtx = useAccordionItemContext();
+
+  return (
+    <div
+      id={itemCtx.contentId}
+      role="region"
+      aria-labelledby={itemCtx.triggerId}
+      hidden={!itemCtx.isExpanded() || undefined}
+      data-state={itemCtx.isExpanded() ? "open" : "closed"}
+      {...rest}
+    >
+      {local.children}
+    </div>
+  );
+}
diff --git a/packages/core/src/components/accordion/accordion-context.ts b/packages/core/src/components/accordion/accordion-context.ts
new file mode 100644
index 0000000..2c54638
--- /dev/null
+++ b/packages/core/src/components/accordion/accordion-context.ts
@@ -0,0 +1,40 @@
+import type { Accessor } from "solid-js";
+import { createContext, useContext } from "solid-js";
+
+export interface AccordionRootContextValue {
+  isExpanded: (value: string) => boolean;
+  toggleItem: (value: string) => void;
+  disabled: Accessor<boolean>;
+}
+
+export interface AccordionItemContextValue {
+  value: string;
+  isExpanded: Accessor<boolean>;
+  triggerId: string;
+  contentId: string;
+}
+
+const AccordionRootContext = createContext<AccordionRootContextValue>();
+const AccordionItemContext = createContext<AccordionItemContextValue>();
+
+/**
+ * Returns the Accordion root context. Throws if used outside <Accordion>.
+ */
+export function useAccordionRootContext(): AccordionRootContextValue {
+  const ctx = useContext(AccordionRootContext);
+  if (!ctx) throw new Error("[PettyUI] Accordion parts must be used inside <Accordion>.");
+  return ctx;
+}
+
+/**
+ * Returns the AccordionItem context. Throws if used outside <Accordion.Item>.
+ */
+export function useAccordionItemContext(): AccordionItemContextValue {
+  const ctx = useContext(AccordionItemContext);
+  if (!ctx)
+    throw new Error("[PettyUI] Accordion.Trigger/Content must be used inside <Accordion.Item>.");
+  return ctx;
+}
+
+export const AccordionRootContextProvider = AccordionRootContext.Provider;
+export const AccordionItemContextProvider = AccordionItemContext.Provider;
diff --git a/packages/core/src/components/accordion/accordion-header.tsx b/packages/core/src/components/accordion/accordion-header.tsx
new file mode 100644
index 0000000..40ab31f
--- /dev/null
+++ b/packages/core/src/components/accordion/accordion-header.tsx
@@ -0,0 +1,19 @@
+import type { JSX } from "solid-js";
+import { splitProps } from "solid-js";
+import { Dynamic } from "solid-js/web";
+
+export interface AccordionHeaderProps extends JSX.HTMLAttributes<HTMLHeadingElement> {
+  /** Heading level element. @default "h3" */
+  as?: string;
+  children?: JSX.Element;
+}
+
+/** Heading wrapper for an Accordion trigger. Defaults to h3. */
+export function AccordionHeader(props: AccordionHeaderProps): JSX.Element {
+  const [local, rest] = splitProps(props, ["as", "children"]);
+  return (
+    <Dynamic component={local.as ?? "h3"} {...rest}>
+      {local.children}
+    </Dynamic>
+  );
+}
diff --git a/packages/core/src/components/accordion/accordion-item.tsx b/packages/core/src/components/accordion/accordion-item.tsx
new file mode 100644
index 0000000..fdb202d
--- /dev/null
+++ b/packages/core/src/components/accordion/accordion-item.tsx
@@ -0,0 +1,36 @@
+import type { JSX } from "solid-js";
+import { createUniqueId, splitProps } from "solid-js";
+import { AccordionItemContextProvider, useAccordionRootContext } from "./accordion-context";
+
+export interface AccordionItemProps extends JSX.HTMLAttributes<HTMLDivElement> {
+  value: string;
+  disabled?: boolean;
+  children: JSX.Element;
+}
+
+/** A single collapsible item within an Accordion. */
+export function AccordionItem(props: AccordionItemProps): JSX.Element {
+  const [local, rest] = splitProps(props, ["value", "disabled", "children"]);
+  const rootCtx = useAccordionRootContext();
+  const triggerId = createUniqueId();
+  const contentId = createUniqueId();
+
+  const itemCtx = {
+    value: local.value,
+    isExpanded: () => rootCtx.isExpanded(local.value),
+    triggerId,
+    contentId,
+  };
+
+  return (
+    <AccordionItemContextProvider value={itemCtx}>
+      <div
+        data-state={rootCtx.isExpanded(local.value) ? "open" : "closed"}
+        data-disabled={local.disabled || undefined}
+        {...rest}
+      >
+        {local.children}
+      </div>
+    </AccordionItemContextProvider>
+  );
+}
diff --git a/packages/core/src/components/accordion/accordion-root.tsx b/packages/core/src/components/accordion/accordion-root.tsx
new file mode 100644
index 0000000..62cbd01
--- /dev/null
+++ b/packages/core/src/components/accordion/accordion-root.tsx
@@ -0,0 +1,70 @@
+import type { JSX } from "solid-js";
+import { createSignal, splitProps } from "solid-js";
+import { AccordionRootContextProvider, type AccordionRootContextValue } from "./accordion-context";
+
+export interface AccordionRootProps extends JSX.HTMLAttributes<HTMLDivElement> {
+  /** "single" allows one item open at a time; "multiple" allows any number. @default "single" */
+  type?: "single" | "multiple";
+  /** In single mode, whether the open item can be closed by clicking it again. @default false */
+  collapsible?: boolean;
+  value?: string | string[];
+  defaultValue?: string | string[];
+  onValueChange?: (value: string | string[]) => void;
+  disabled?: boolean;
+  children: JSX.Element;
+}
+
+/**
+ * Root container for an accordion. Manages which items are expanded.
+ */
+export function AccordionRoot(props: AccordionRootProps): JSX.Element {
+  const [local, rest] = splitProps(props, [
+    "type",
+    "collapsible",
+    "value",
+    "defaultValue",
+    "onValueChange",
+    "disabled",
+    "children",
+  ]);
+
+  const type = () => local.type ?? "single";
+
+  const normalize = (v: string | string[] | undefined): string[] => {
+    if (v === undefined) return [];
+    return Array.isArray(v) ? v : [v];
+  };
+
+  const [expandedValues, setExpandedValues] = createSignal<string[]>(normalize(local.defaultValue));
+
+  const getValues = (): string[] =>
+    local.value !== undefined ? normalize(local.value) : expandedValues();
+
+  const ctx: AccordionRootContextValue = {
+    isExpanded: (value) => getValues().includes(value),
+    toggleItem: (value) => {
+      const current = getValues();
+      let next: string[];
+      if (type() === "single") {
+        if (current.includes(value)) {
+          next = local.collapsible ? [] : current;
+        } else {
+          next = [value];
+        }
+      } else {
+        next = current.includes(value) ? current.filter((v) => v !== value) : [...current, value];
+      }
+      if (local.value === undefined) setExpandedValues(next);
+      local.onValueChange?.(type() === "multiple" ? next : (next[0] ?? ""));
+    },
+    disabled: () => local.disabled ?? false,
+  };
+
+  return (
+    <AccordionRootContextProvider value={ctx}>
+      <div data-accordion-root data-disabled={local.disabled || undefined} {...rest}>
+        {local.children}
+      </div>
+    </AccordionRootContextProvider>
+  );
+}
diff --git a/packages/core/src/components/accordion/accordion-trigger.tsx b/packages/core/src/components/accordion/accordion-trigger.tsx
new file mode 100644
index 0000000..d73ff9a
--- /dev/null
+++ b/packages/core/src/components/accordion/accordion-trigger.tsx
@@ -0,0 +1,55 @@
+import type { JSX } from "solid-js";
+import { splitProps } from "solid-js";
+import { useAccordionItemContext, useAccordionRootContext } from "./accordion-context";
+
+export interface AccordionTriggerProps extends JSX.ButtonHTMLAttributes<HTMLButtonElement> {
+  children?: JSX.Element;
+}
+
+/** Button that toggles an Accordion item open/closed. Supports ArrowDown/ArrowUp/Home/End navigation. */
+export function AccordionTrigger(props: AccordionTriggerProps): JSX.Element {
+  const [local, rest] = splitProps(props, ["children"]);
+  const rootCtx = useAccordionRootContext();
+  const itemCtx = useAccordionItemContext();
+
+  return (
+    <button
+      type="button"
+      id={itemCtx.triggerId}
+      aria-expanded={itemCtx.isExpanded() ? "true" : "false"}
+      aria-controls={itemCtx.contentId}
+      data-state={itemCtx.isExpanded() ? "open" : "closed"}
+      data-accordion-trigger
+      disabled={rootCtx.disabled()}
+      {...rest}
+      onClick={(e) => {
+        if (typeof rest.onClick === "function") rest.onClick(e);
+        if (!rootCtx.disabled()) rootCtx.toggleItem(itemCtx.value);
+      }}
+      onKeyDown={(e) => {
+        if (typeof rest.onKeyDown === "function") rest.onKeyDown(e);
+        const accordion = (e.currentTarget as HTMLButtonElement).closest("[data-accordion-root]");
+        if (!accordion) return;
+        const triggers = Array.from(
+          accordion.querySelectorAll<HTMLButtonElement>("[data-accordion-trigger]"),
+        );
+        const index = triggers.indexOf(e.currentTarget as HTMLButtonElement);
+        if (e.key === "ArrowDown") {
+          e.preventDefault();
+          triggers[(index + 1) % triggers.length]?.focus();
+        } else if (e.key === "ArrowUp") {
+          e.preventDefault();
+          triggers[(index - 1 + triggers.length) % triggers.length]?.focus();
+        } else if (e.key === "Home") {
+          e.preventDefault();
+          triggers[0]?.focus();
+        } else if (e.key === "End") {
+          e.preventDefault();
+          triggers[triggers.length - 1]?.focus();
+        }
+      }}
+    >
+      {local.children}
+    </button>
+  );
+}
diff --git a/packages/core/src/components/accordion/index.ts b/packages/core/src/components/accordion/index.ts
new file mode 100644
index 0000000..ea51fcd
--- /dev/null
+++ b/packages/core/src/components/accordion/index.ts
@@ -0,0 +1,21 @@
+import { AccordionContent } from "./accordion-content";
+import { useAccordionRootContext } from "./accordion-context";
+import { AccordionHeader } from "./accordion-header";
+import { AccordionItem } from "./accordion-item";
+import { AccordionRoot } from "./accordion-root";
+import { AccordionTrigger } from "./accordion-trigger";
+
+export const Accordion = Object.assign(AccordionRoot, {
+  Item: AccordionItem,
+  Header: AccordionHeader,
+  Trigger: AccordionTrigger,
+  Content: AccordionContent,
+  useContext: useAccordionRootContext,
+});
+
+export type { AccordionRootProps } from "./accordion-root";
+export type { AccordionItemProps } from "./accordion-item";
+export type { AccordionHeaderProps } from "./accordion-header";
+export type { AccordionTriggerProps } from "./accordion-trigger";
+export type { AccordionContentProps } from "./accordion-content";
+export type { AccordionRootContextValue, AccordionItemContextValue } from "./accordion-context";
diff --git a/packages/core/tests/components/accordion/accordion.test.tsx b/packages/core/tests/components/accordion/accordion.test.tsx
new file mode 100644
index 0000000..3bba495
--- /dev/null
+++ b/packages/core/tests/components/accordion/accordion.test.tsx
@@ -0,0 +1,114 @@
+import { fireEvent, render, screen } from "@solidjs/testing-library";
+import { describe, expect, it } from "vitest";
+import { Accordion } from "../../../src/components/accordion/index";
+
+describe("Accordion", () => {
+  it("all items closed by default", () => {
+    render(() => (
+      <Accordion>
+        <Accordion.Item value="a">
+          <Accordion.Header><Accordion.Trigger>A</Accordion.Trigger></Accordion.Header>
+          <Accordion.Content data-testid="content-a">Content A</Accordion.Content>
+        </Accordion.Item>
+      </Accordion>
+    ));
+    expect(screen.getByTestId("content-a")).toHaveAttribute("hidden");
+  });
+
+  it("clicking trigger opens item", () => {
+    render(() => (
+      <Accordion>
+        <Accordion.Item value="a">
+          <Accordion.Header><Accordion.Trigger>A</Accordion.Trigger></Accordion.Header>
+          <Accordion.Content data-testid="content-a">Content A</Accordion.Content>
+        </Accordion.Item>
+      </Accordion>
+    ));
+    fireEvent.click(screen.getByRole("button"));
+    expect(screen.getByTestId("content-a")).not.toHaveAttribute("hidden");
+  });
+
+  it("single mode: opening one closes another", () => {
+    render(() => (
+      <Accordion type="single" defaultValue="a">
+        <Accordion.Item value="a">
+          <Accordion.Header><Accordion.Trigger>A</Accordion.Trigger></Accordion.Header>
+          <Accordion.Content data-testid="content-a">Content A</Accordion.Content>
+        </Accordion.Item>
+        <Accordion.Item value="b">
+          <Accordion.Header><Accordion.Trigger>B</Accordion.Trigger></Accordion.Header>
+          <Accordion.Content data-testid="content-b">Content B</Accordion.Content>
+        </Accordion.Item>
+      </Accordion>
+    ));
+    expect(screen.getByTestId("content-a")).not.toHaveAttribute("hidden");
+    fireEvent.click(screen.getAllByRole("button")[1]);
+    expect(screen.getByTestId("content-a")).toHaveAttribute("hidden");
+    expect(screen.getByTestId("content-b")).not.toHaveAttribute("hidden");
+  });
+
+  it("single mode with collapsible=true: clicking open item closes it", () => {
+    render(() => (
+      <Accordion type="single" collapsible defaultValue="a">
+        <Accordion.Item value="a">
+          <Accordion.Header><Accordion.Trigger>A</Accordion.Trigger></Accordion.Header>
+          <Accordion.Content data-testid="content-a">Content A</Accordion.Content>
+        </Accordion.Item>
+      </Accordion>
+    ));
+    fireEvent.click(screen.getByRole("button"));
+    expect(screen.getByTestId("content-a")).toHaveAttribute("hidden");
+  });
+
+  it("multiple mode: multiple items can be open", () => {
+    render(() => (
+      <Accordion type="multiple">
+        <Accordion.Item value="a">
+          <Accordion.Header><Accordion.Trigger>A</Accordion.Trigger></Accordion.Header>
+          <Accordion.Content data-testid="content-a">Content A</Accordion.Content>
+        </Accordion.Item>
+        <Accordion.Item value="b">
+          <Accordion.Header><Accordion.Trigger>B</Accordion.Trigger></Accordion.Header>
+          <Accordion.Content data-testid="content-b">Content B</Accordion.Content>
+        </Accordion.Item>
+      </Accordion>
+    ));
+    fireEvent.click(screen.getAllByRole("button")[0]);
+    fireEvent.click(screen.getAllByRole("button")[1]);
+    expect(screen.getByTestId("content-a")).not.toHaveAttribute("hidden");
+    expect(screen.getByTestId("content-b")).not.toHaveAttribute("hidden");
+  });
+
+  it("trigger has aria-expanded", () => {
+    render(() => (
+      <Accordion>
+        <Accordion.Item value="a">
+          <Accordion.Header><Accordion.Trigger>A</Accordion.Trigger></Accordion.Header>
+          <Accordion.Content>Content A</Accordion.Content>
+        </Accordion.Item>
+      </Accordion>
+    ));
+    expect(screen.getByRole("button").getAttribute("aria-expanded")).toBe("false");
+    fireEvent.click(screen.getByRole("button"));
+    expect(screen.getByRole("button").getAttribute("aria-expanded")).toBe("true");
+  });
+
+  it("ArrowDown moves focus to next trigger", () => {
+    render(() => (
+      <Accordion>
+        <Accordion.Item value="a">
+          <Accordion.Header><Accordion.Trigger>A</Accordion.Trigger></Accordion.Header>
+          <Accordion.Content>Content A</Accordion.Content>
+        </Accordion.Item>
+        <Accordion.Item value="b">
+          <Accordion.Header><Accordion.Trigger>B</Accordion.Trigger></Accordion.Header>
+          <Accordion.Content>Content B</Accordion.Content>
+        </Accordion.Item>
+      </Accordion>
+    ));
+    const [first] = screen.getAllByRole("button");
+    first.focus();
+    fireEvent.keyDown(first, { key: "ArrowDown" });
+    expect(document.activeElement).toBe(screen.getAllByRole("button")[1]);
+  });
+});