diff --git a/src/pseudo-selectors/aliases.ts b/src/pseudo-selectors/aliases.ts
index eeaae33c..8ad6c128 100644
--- a/src/pseudo-selectors/aliases.ts
+++ b/src/pseudo-selectors/aliases.ts
@@ -7,6 +7,11 @@
 const textControl =
     "input:is([type=text i],[type=search i],[type=url i],[type=tel i],[type=email i],[type=password i],[type=date i],[type=month i],[type=week i],[type=time i],[type=datetime-local i],[type=number i])";
 
+const disabledByFieldset = `:is(
+    fieldset[disabled] > :not(legend:first-of-type),
+    fieldset[disabled] > :not(legend:first-of-type) *
+)`;
+
 /**
  * Aliases are pseudos that are expressed as selectors.
  */
@@ -20,9 +25,10 @@ export const aliases: Record<string, string> = {
 
     // https://html.spec.whatwg.org/multipage/scripting.html#disabled-elements
     disabled: `:is(
-        :is(button, input, select, textarea, optgroup, option)[disabled],
+        :is(button, input, select, textarea, optgroup, option, fieldset)[disabled],
         optgroup[disabled] > option,
-        fieldset[disabled]:not(fieldset[disabled] legend:first-of-type *)
+        :is(button, input, select, textarea, fieldset)${disabledByFieldset},
+        :is(optgroup, option):is(select[disabled] *, select${disabledByFieldset} *)
     )`,
     enabled:
         ":is(button, input, select, textarea, optgroup, option, fieldset):not(:disabled)",
diff --git a/src/pseudo-selectors/index.ts b/src/pseudo-selectors/index.ts
index b4cf903d..5eebe045 100644
--- a/src/pseudo-selectors/index.ts
+++ b/src/pseudo-selectors/index.ts
@@ -60,7 +60,15 @@ export function compilePseudoSelector<Node, ElementNode extends Node>(
 
         // The alias has to be parsed here, to make sure options are respected.
         const alias = parse(stringPseudo);
-        return subselects["is"](next, alias, options, context, compileToken);
+        const isDisabledAlias = name === "disabled" && userPseudo === undefined;
+        // Disabled state can depend on ancestors outside the search context.
+        return subselects["is"](
+            next,
+            alias,
+            isDisabledAlias ? { ...options, relativeSelector: false } : options,
+            isDisabledAlias ? undefined : context,
+            compileToken,
+        );
     }
 
     if (typeof userPseudo === "function") {
diff --git a/test/pseudo-classes.ts b/test/pseudo-classes.ts
index 1feeb8ce..4fa794b1 100644
--- a/test/pseudo-classes.ts
+++ b/test/pseudo-classes.ts
@@ -213,6 +213,157 @@ describe(":has", () => {
     });
 });
 
+describe(":disabled fieldsets", () => {
+    it("should inherit a disabled select's state for options and optgroups", () => {
+        const dom = parseDocument(
+            '<select disabled><optgroup id="group"><option id="option">X</option></optgroup></select>',
+        );
+        expect(
+            CSSselect.selectAll<AnyNode, Element>(
+                "optgroup:disabled, option:disabled",
+                dom,
+            ).map((element) => element.attribs["id"]),
+        ).toStrictEqual(["group", "option"]);
+        expect(
+            CSSselect.selectAll("optgroup:enabled, option:enabled", dom),
+        ).toHaveLength(0);
+    });
+
+    it("should exempt a select and its options inside the first legend", () => {
+        const dom = parseDocument(
+            '<fieldset disabled><legend><select><optgroup id="group"><option id="option">X</option></optgroup></select></legend></fieldset>',
+        );
+        expect(
+            CSSselect.selectAll("optgroup:disabled, option:disabled", dom),
+        ).toHaveLength(0);
+        expect(
+            CSSselect.selectAll<AnyNode, Element>(
+                "optgroup:enabled, option:enabled",
+                dom,
+            ).map((element) => element.attribs["id"]),
+        ).toStrictEqual(["group", "option"]);
+    });
+
+    it("should not inherit fieldset disabled state without an ancestor select", () => {
+        const dom = parseDocument(
+            '<fieldset disabled><optgroup id="group"><option id="option">X</option></optgroup></fieldset>',
+        );
+        expect(
+            CSSselect.selectAll("optgroup:disabled, option:disabled", dom),
+        ).toHaveLength(0);
+    });
+
+    it("should find disabled ancestors above a scoped search root", () => {
+        const dom = parseDocument(
+            '<fieldset disabled><div id="root"><input id="input"></div></fieldset>',
+        );
+        const root = CSSselect.selectAll<AnyNode, Element>("#root", dom)[0];
+        expect(
+            CSSselect.selectAll<AnyNode, Element>(":disabled", root).map(
+                (element) => element.attribs["id"],
+            ),
+        ).toStrictEqual(["input"]);
+        expect(CSSselect.selectAll(":enabled", root)).toHaveLength(0);
+        expect(
+            CSSselect.selectAll(":disabled", [root], { cacheResults: false }),
+        ).toHaveLength(1);
+        expect(
+            CSSselect.selectAll(":disabled", root, { context: root }),
+        ).toHaveLength(1);
+        const input = CSSselect.selectAll<AnyNode, Element>("input", root)[0];
+        expect(CSSselect.is(input, ":disabled", { context: root })).toBe(true);
+        expect(CSSselect.is(input, ":enabled", { context: root })).toBe(false);
+    });
+
+    it("should preserve the query context for a custom disabled alias", () => {
+        const dom = parseDocument(
+            '<fieldset disabled><div id="root"><input></div></fieldset>',
+        );
+        const root = CSSselect.selectAll<AnyNode, Element>("#root", dom)[0];
+        expect(
+            CSSselect.selectAll(":disabled", root, {
+                pseudos: { disabled: "fieldset input" },
+            }),
+        ).toHaveLength(0);
+    });
+
+    it("should keep the legend exemption when it is above the search root", () => {
+        const dom = parseDocument(
+            '<fieldset disabled><legend><div id="root"><input id="input"></div></legend></fieldset>',
+        );
+        const root = CSSselect.selectAll<AnyNode, Element>("#root", dom)[0];
+        expect(CSSselect.selectAll(":disabled", root)).toHaveLength(0);
+        expect(
+            CSSselect.selectAll<AnyNode, Element>(":enabled", root).map(
+                (element) => element.attribs["id"],
+            ),
+        ).toStrictEqual(["input"]);
+    });
+
+    it("should disable direct and nested controls, but not arbitrary descendants", () => {
+        const dom = parseDocument(
+            '<fieldset disabled id="fieldset"><input id="input"><div id="div"><button id="button">X</button><select id="select"><option id="option">X</option></select><textarea id="textarea"></textarea></div></fieldset>',
+        );
+        expect(
+            CSSselect.selectAll<AnyNode, Element>(":disabled", dom).map(
+                (element) => element.attribs["id"],
+            ),
+        ).toStrictEqual([
+            "fieldset",
+            "input",
+            "button",
+            "select",
+            "option",
+            "textarea",
+        ]);
+        expect(
+            CSSselect.selectAll<AnyNode, Element>(":enabled", dom).map(
+                (element) => element.attribs["id"],
+            ),
+        ).toStrictEqual([]);
+    });
+
+    it("should exempt only the first direct legend", () => {
+        const dom = parseDocument(
+            '<fieldset disabled><div></div><legend><input id="first"></legend><legend><input id="second"></legend></fieldset>',
+        );
+        expect(
+            CSSselect.selectAll<AnyNode, Element>("input:disabled", dom).map(
+                (element) => element.attribs["id"],
+            ),
+        ).toStrictEqual(["second"]);
+        expect(
+            CSSselect.selectAll<AnyNode, Element>("input:enabled", dom).map(
+                (element) => element.attribs["id"],
+            ),
+        ).toStrictEqual(["first"]);
+    });
+
+    it("should not exempt a nested fieldset legend from an outer disabled fieldset", () => {
+        const dom = parseDocument(
+            '<fieldset disabled><fieldset id="inner"><legend><input id="nested"></legend></fieldset></fieldset>',
+        );
+        expect(
+            CSSselect.selectAll<AnyNode, Element>(
+                "#inner:disabled, input:disabled",
+                dom,
+            ).map((element) => element.attribs["id"]),
+        ).toStrictEqual(["inner", "nested"]);
+    });
+
+    it("should still match an explicitly disabled fieldset inside an exempt legend", () => {
+        const dom = parseDocument(
+            '<fieldset disabled><legend><fieldset disabled id="inner"><input id="nested"></fieldset></legend></fieldset>',
+        );
+        expect(
+            CSSselect.selectAll<AnyNode, Element>(
+                "#inner:disabled, input:disabled",
+                dom,
+            ).map((element) => element.attribs["id"]),
+        ).toStrictEqual(["inner", "nested"]);
+    });
+});
+
 describe(":enabled", () => {
     it("should match form-associated elements", () => {
         const dom = parseDocument(`