diff --git a/CHANGELOG.md b/CHANGELOG.md
index 19d63d4..43b9751 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -18,6 +18,7 @@ and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0
 - Improve React peer dependency version range ([#544](https://github.com/tailwindlabs/headlessui/pull/544))
 - Improve types for the `open` prop in the `Dialog` component ([#550](https://github.com/tailwindlabs/headlessui/pull/550))
 - Improve `aria-expanded` logic ([#592](https://github.com/tailwindlabs/headlessui/pull/592))
+- Remove undocumented `:className` prop ([#607](https://github.com/tailwindlabs/headlessui/pull/607))
 
 ## [Unreleased - Vue]
 
diff --git a/packages/@headlessui-vue/examples/src/components/Home.vue b/packages/@headlessui-vue/examples/src/components/Home.vue
index 408606f..91a870f 100644
--- a/packages/@headlessui-vue/examples/src/components/Home.vue
+++ b/packages/@headlessui-vue/examples/src/components/Home.vue
@@ -1,6 +1,6 @@
 <template>
-  <div className="container my-24">
-    <div className="prose">
+  <div class="container my-24">
+    <div class="prose">
       <h2>Examples</h2>
       <Examples :examples="examples" />
     </div>
diff --git a/packages/@headlessui-vue/src/components/listbox/listbox.test.tsx b/packages/@headlessui-vue/src/components/listbox/listbox.test.tsx
index 790d0db..398a4ba 100644
--- a/packages/@headlessui-vue/src/components/listbox/listbox.test.tsx
+++ b/packages/@headlessui-vue/src/components/listbox/listbox.test.tsx
@@ -479,84 +479,6 @@ describe('Rendering', () => {
 })
 
 describe('Rendering composition', () => {
-  it(
-    'should be possible to conditionally render classNames (aka className can be a function?!)',
-    suppressConsoleLogs(async () => {
-      renderTemplate({
-        template: html`
-          <Listbox v-model="value">
-            <ListboxButton>Trigger</ListboxButton>
-            <ListboxOptions>
-              <ListboxOption value="a" :className="JSON.stringify">
-                Option A
-              </ListboxOption>
-              <ListboxOption value="b" disabled :className="JSON.stringify">
-                Option B
-              </ListboxOption>
-              <ListboxOption value="c" className="no-special-treatment">
-                Option C
-              </ListboxOption>
-            </ListboxOptions>
-          </Listbox>
-        `,
-        setup: () => ({ value: ref(null) }),
-      })
-
-      assertListboxButton({
-        state: ListboxState.InvisibleUnmounted,
-        attributes: { id: 'headlessui-listbox-button-1' },
-      })
-      assertListbox({ state: ListboxState.InvisibleUnmounted })
-
-      // Open Listbox
-      await click(getListboxButton())
-
-      let options = getListboxOptions()
-
-      // Verify correct classNames
-      expect('' + options[0].classList).toEqual(
-        JSON.stringify({ active: false, selected: false, disabled: false })
-      )
-      expect('' + options[1].classList).toEqual(
-        JSON.stringify({ active: false, selected: false, disabled: true })
-      )
-      expect('' + options[2].classList).toEqual('no-special-treatment')
-
-      // Double check that nothing is active
-      assertNoActiveListboxOption(getListbox())
-
-      // Make the first option active
-      await press(Keys.ArrowDown)
-
-      // Verify the classNames
-      expect('' + options[0].classList).toEqual(
-        JSON.stringify({ active: true, selected: false, disabled: false })
-      )
-      expect('' + options[1].classList).toEqual(
-        JSON.stringify({ active: false, selected: false, disabled: true })
-      )
-      expect('' + options[2].classList).toEqual('no-special-treatment')
-
-      // Double check that the first option is the active one
-      assertActiveListboxOption(options[0])
-
-      // Let's go down, this should go to the third option since the second option is disabled!
-      await press(Keys.ArrowDown)
-
-      // Verify the classNames
-      expect('' + options[0].classList).toEqual(
-        JSON.stringify({ active: false, selected: false, disabled: false })
-      )
-      expect('' + options[1].classList).toEqual(
-        JSON.stringify({ active: false, selected: false, disabled: true })
-      )
-      expect('' + options[2].classList).toEqual('no-special-treatment')
-
-      // Double check that the last option is the active one
-      assertActiveListboxOption(options[2])
-    })
-  )
-
   it(
     'should be possible to swap the Listbox option with a button for example',
     suppressConsoleLogs(async () => {
diff --git a/packages/@headlessui-vue/src/components/listbox/listbox.ts b/packages/@headlessui-vue/src/components/listbox/listbox.ts
index 983bd2d..1aab640 100644
--- a/packages/@headlessui-vue/src/components/listbox/listbox.ts
+++ b/packages/@headlessui-vue/src/components/listbox/listbox.ts
@@ -19,7 +19,6 @@ import { Features, render, omit } from '../../utils/render'
 import { useId } from '../../hooks/use-id'
 import { Keys } from '../../keyboard'
 import { calculateActiveIndex, Focus } from '../../utils/calculate-active-index'
-import { resolvePropValue } from '../../utils/resolve-prop-value'
 import { dom } from '../../utils/dom'
 import { useWindowEvent } from '../../hooks/use-window-event'
 import { useOpenClosed, State, useOpenClosedProvider } from '../../internal/open-closed'
@@ -474,7 +473,6 @@ export let ListboxOption = defineComponent({
     value: { type: [Object, String] },
     disabled: { type: Boolean, default: false },
     class: { type: [String, Function], required: false },
-    className: { type: [String, Function], required: false },
   },
   setup(props, { slots, attrs }) {
     let api = useListboxContext('ListboxOption')
@@ -548,13 +546,13 @@ export let ListboxOption = defineComponent({
     }
 
     return () => {
-      let { disabled, class: defaultClass, className = defaultClass } = props
+      let { disabled, class: defaultClass } = props
       let slot = { active: active.value, selected: selected.value, disabled }
       let propsWeControl = {
         id,
         role: 'option',
         tabIndex: disabled === true ? undefined : -1,
-        class: resolvePropValue(className, slot),
+        class: defaultClass,
         'aria-disabled': disabled === true ? true : undefined,
         'aria-selected': selected.value === true ? selected.value : undefined,
         disabled: undefined, // Never forward the `disabled` prop
diff --git a/packages/@headlessui-vue/src/components/menu/menu.test.tsx b/packages/@headlessui-vue/src/components/menu/menu.test.tsx
index 21db2d3..311d356 100644
--- a/packages/@headlessui-vue/src/components/menu/menu.test.tsx
+++ b/packages/@headlessui-vue/src/components/menu/menu.test.tsx
@@ -633,60 +633,6 @@ describe('Rendering', () => {
 })
 
 describe('Rendering composition', () => {
-  it('should be possible to conditionally render classNames (aka className can be a function?!)', async () => {
-    renderTemplate(jsx`
-      <Menu>
-        <MenuButton>Trigger</MenuButton>
-        <MenuItems>
-          <MenuItem as="a" :className="JSON.stringify">Item A</MenuItem>
-          <MenuItem as="a" disabled :className="JSON.stringify">Item B</MenuItem>
-          <MenuItem as="a" class="no-special-treatment">Item C</MenuItem>
-        </MenuItems>
-      </Menu>
-    `)
-
-    assertMenuButton({
-      state: MenuState.InvisibleUnmounted,
-      attributes: { id: 'headlessui-menu-button-1' },
-    })
-    assertMenu({ state: MenuState.InvisibleUnmounted })
-
-    // Open menu
-    await click(getMenuButton())
-
-    let items = getMenuItems()
-
-    // Verify correct classNames
-    expect('' + items[0].classList).toEqual(JSON.stringify({ active: false, disabled: false }))
-    expect('' + items[1].classList).toEqual(JSON.stringify({ active: false, disabled: true }))
-    expect('' + items[2].classList).toEqual('no-special-treatment')
-
-    // Double check that nothing is active
-    assertNoActiveMenuItem()
-
-    // Make the first item active
-    await press(Keys.ArrowDown)
-
-    // Verify the classNames
-    expect('' + items[0].classList).toEqual(JSON.stringify({ active: true, disabled: false }))
-    expect('' + items[1].classList).toEqual(JSON.stringify({ active: false, disabled: true }))
-    expect('' + items[2].classList).toEqual('no-special-treatment')
-
-    // Double check that the first item is the active one
-    assertMenuLinkedWithMenuItem(items[0])
-
-    // Let's go down, this should go to the third item since the second item is disabled!
-    await press(Keys.ArrowDown)
-
-    // Verify the classNames
-    expect('' + items[0].classList).toEqual(JSON.stringify({ active: false, disabled: false }))
-    expect('' + items[1].classList).toEqual(JSON.stringify({ active: false, disabled: true }))
-    expect('' + items[2].classList).toEqual('no-special-treatment')
-
-    // Double check that the last item is the active one
-    assertMenuLinkedWithMenuItem(items[2])
-  })
-
   it(
     'should be possible to swap the menu item with a button for example',
     suppressConsoleLogs(async () => {
@@ -734,22 +680,22 @@ describe('Rendering composition', () => {
         template: jsx`
           <Menu>
             <MenuButton>Trigger</MenuButton>
-            <div className="outer">
+            <div class="outer">
               <MenuItems>
-                <div className="py-1 inner">
+                <div class="py-1 inner">
                   <MenuItem as="button">Item A</MenuItem>
                   <MenuItem as="button">Item B</MenuItem>
                 </div>
-                <div className="py-1 inner">
+                <div class="py-1 inner">
                   <MenuItem as="button">Item C</MenuItem>
                   <MenuItem>
                     <div>
-                      <div className="outer">Item D</div>
+                      <div class="outer">Item D</div>
                     </div>
                   </MenuItem>
                 </div>
-                <div className="py-1 inner">
-                  <form className="inner">
+                <div class="py-1 inner">
+                  <form class="inner">
                     <MenuItem as="button">Item E</MenuItem>
                   </form>
                 </div>
diff --git a/packages/@headlessui-vue/src/components/menu/menu.ts b/packages/@headlessui-vue/src/components/menu/menu.ts
index 85e0879..75e9630 100644
--- a/packages/@headlessui-vue/src/components/menu/menu.ts
+++ b/packages/@headlessui-vue/src/components/menu/menu.ts
@@ -15,7 +15,6 @@ import { Features, render } from '../../utils/render'
 import { useId } from '../../hooks/use-id'
 import { Keys } from '../../keyboard'
 import { Focus, calculateActiveIndex } from '../../utils/calculate-active-index'
-import { resolvePropValue } from '../../utils/resolve-prop-value'
 import { dom } from '../../utils/dom'
 import { useWindowEvent } from '../../hooks/use-window-event'
 import { useTreeWalker } from '../../hooks/use-tree-walker'
@@ -413,7 +412,6 @@ export let MenuItem = defineComponent({
     as: { type: [Object, String], default: 'template' },
     disabled: { type: Boolean, default: false },
     class: { type: [String, Function], required: false },
-    className: { type: [String, Function], required: false },
   },
   setup(props, { slots, attrs }) {
     let api = useMenuContext('MenuItem')
@@ -467,13 +465,13 @@ export let MenuItem = defineComponent({
     }
 
     return () => {
-      let { disabled, class: defaultClass, className = defaultClass } = props
+      let { disabled, class: defaultClass } = props
       let slot = { active: active.value, disabled }
       let propsWeControl = {
         id,
         role: 'menuitem',
         tabIndex: disabled === true ? undefined : -1,
-        class: resolvePropValue(className, slot),
+        class: defaultClass,
         'aria-disabled': disabled === true ? true : undefined,
         onClick: handleClick,
         onFocus: handleFocus,
diff --git a/packages/@headlessui-vue/src/components/radio-group/radio-group.ts b/packages/@headlessui-vue/src/components/radio-group/radio-group.ts
index 0c3b05b..6750f82 100644
--- a/packages/@headlessui-vue/src/components/radio-group/radio-group.ts
+++ b/packages/@headlessui-vue/src/components/radio-group/radio-group.ts
@@ -20,7 +20,6 @@ import { useId } from '../../hooks/use-id'
 import { render } from '../../utils/render'
 import { Label, useLabels } from '../label/label'
 import { Description, useDescriptions } from '../description/description'
-import { resolvePropValue } from '../../utils/resolve-prop-value'
 import { useTreeWalker } from '../../hooks/use-tree-walker'
 
 interface Option {
@@ -234,16 +233,9 @@ export let RadioGroupOption = defineComponent({
     value: { type: [Object, String, Number, Boolean] },
     disabled: { type: Boolean, default: false },
     class: { type: [String, Function], required: false },
-    className: { type: [String, Function], required: false },
   },
   render() {
-    let {
-      value,
-      disabled,
-      class: defaultClass,
-      className = defaultClass,
-      ...passThroughProps
-    } = this.$props
+    let { value, disabled, class: defaultClass, ...passThroughProps } = this.$props
 
     let slot = {
       checked: this.checked,
@@ -255,7 +247,7 @@ export let RadioGroupOption = defineComponent({
       id: this.id,
       ref: 'el',
       role: 'radio',
-      class: resolvePropValue(className, slot),
+      class: defaultClass,
       'aria-checked': this.checked ? 'true' : 'false',
       'aria-labelledby': this.labelledby,
       'aria-describedby': this.describedby,
diff --git a/packages/@headlessui-vue/src/components/switch/switch.ts b/packages/@headlessui-vue/src/components/switch/switch.ts
index 6eb0f17..b9db0d4 100644
--- a/packages/@headlessui-vue/src/components/switch/switch.ts
+++ b/packages/@headlessui-vue/src/components/switch/switch.ts
@@ -12,7 +12,6 @@ import {
 import { render } from '../../utils/render'
 import { useId } from '../../hooks/use-id'
 import { Keys } from '../../keyboard'
-import { resolvePropValue } from '../../utils/resolve-prop-value'
 import { Label, useLabels } from '../label/label'
 import { Description, useDescriptions } from '../description/description'
 
@@ -63,11 +62,10 @@ export let Switch = defineComponent({
     as: { type: [Object, String], default: 'button' },
     modelValue: { type: Boolean, default: false },
     class: { type: [String, Function], required: false },
-    className: { type: [String, Function], required: false },
   },
   render() {
     let api = inject(GroupContext, null)
-    let { class: defaultClass, className = defaultClass } = this.$props
+    let { class: defaultClass } = this.$props
 
     let slot = { checked: this.$props.modelValue }
     let propsWeControl = {
@@ -75,7 +73,7 @@ export let Switch = defineComponent({
       ref: api === null ? undefined : api.switchRef,
       role: 'switch',
       tabIndex: 0,
-      class: resolvePropValue(className, slot),
+      class: defaultClass,
       'aria-checked': this.$props.modelValue,
       'aria-labelledby': this.labelledby,
       'aria-describedby': this.describedby,