diff --git a/docs/src/basics/configuration.dj b/docs/src/basics/configuration.dj
index 2814786..71e4710 100644
--- a/docs/src/basics/configuration.dj
+++ b/docs/src/basics/configuration.dj
@@ -1,6 +1,7 @@
 ---
 order: -1
 ---
+{#config-reference}
 # Configuration reference
 
 {tag=aside .caution}
diff --git a/docs/src/features/version_directives.dj b/docs/src/features/version_directives.dj
new file mode 100644
index 0000000..e23907e
--- /dev/null
+++ b/docs/src/features/version_directives.dj
@@ -0,0 +1,43 @@
+# Version directives
+
+{added-in-version="0.0.5"}
+:::
+:::
+
+You can mark some content as applying to a specific version using the `added-in-version` attribute on an empty div. If you specified a `projectInfo.version`{.language-yaml} in your [configuration](#config-reference), and the specified version is greater, then the message will be future-tense.
+
+```djot
+{added-in-version="0.0.1"}
+:::
+:::
+
+{added-in-version="10.0"}
+:::
+:::
+```
+
+Output:
+
+{added-in-version="0.0.1"}
+:::
+:::
+
+{added-in-version="10.0"}
+:::
+:::
+
+You can also put content inside if you want to add commentary.
+
+```djot
+{added-in-version="10.0"}
+:::
+We're really excited about this feature!
+:::
+```
+
+Output:
+
+{added-in-version="10.0"}
+:::
+We're really excited about this feature!
+:::
\ No newline at end of file
diff --git a/src/engine/executeConfig.ts b/src/engine/executeConfig.ts
index 7b4628e..b6dab23 100644
--- a/src/engine/executeConfig.ts
+++ b/src/engine/executeConfig.ts
@@ -23,6 +23,7 @@ import { SyntaxHighlightingPlugin } from "../plugins/syntaxHighlighting.js";
 import { fileURLToPath } from "url";
 import { IndextermsPlugin } from "../plugins/indextermsPlugin.js";
 import { GFMAlertsPlugin } from "../plugins/gfmAlertsPlugin.js";
+import { VersionDirectivesPlugin } from "../plugins/versionDirectives.js";
 
 function pluralize(n: number, singular: string, plural: string): string {
   return n === 1 ? `1 ${singular}` : `${n} ${plural}`;
@@ -37,6 +38,7 @@ function makeBuiltinPlugins(config: DjockeyConfigResolved): DjockeyPlugin[] {
     new AutoTitlePlugin(),
     new SyntaxHighlightingPlugin(config),
     new GFMAlertsPlugin(),
+    new VersionDirectivesPlugin(config),
   ];
 }
 
diff --git a/src/plugins/versionDirectives.ts b/src/plugins/versionDirectives.ts
new file mode 100644
index 0000000..337f6fd
--- /dev/null
+++ b/src/plugins/versionDirectives.ts
@@ -0,0 +1,84 @@
+import { DjockeyConfig, DjockeyDoc, DjockeyPlugin } from "../types.js";
+import { applyFilter } from "../engine/djotFiltersPlus.js";
+import { getAnyAttribute } from "../util.js";
+import { Block } from "@djot/djot";
+
+function normalizeSemverString(semverString: string): [number, number, number] {
+  const parts: number[] = semverString
+    .split(".")
+    .map((s) => parseInt(s, 10))
+    .slice(0, 3);
+  while (parts.length < 3) parts.push(0);
+  return parts as [number, number, number];
+}
+
+function isSemverGreaterOrEqual(a: string, b: string): boolean {
+  const aParts = normalizeSemverString(a);
+  const bParts = normalizeSemverString(b);
+  for (let i = 0; i < 3; i++) {
+    if (aParts[i] > bParts[i]) return true;
+    if (aParts[i] < bParts[i]) return false;
+  }
+  return true;
+}
+
+type Cls =
+  | "added-in-version"
+  | "changed-in-version"
+  | "removed-in-version"
+  | "deprecated-in-version";
+const PREFIXES_CURRENT: Record<Cls, string> = {
+  "added-in-version": "Added in version",
+  "changed-in-version": "Changed in version",
+  "removed-in-version": "Removed in version",
+  "deprecated-in-version": "Deprecated in version",
+};
+
+const PREFIXES_FUTURE: Record<Cls, string> = {
+  "added-in-version": "Will be added in version",
+  "changed-in-version": "Will be changed in version",
+  "removed-in-version": "Will be reemoved in version",
+  "deprecated-in-version": "Will be deprecated in version",
+};
+
+export class VersionDirectivesPlugin implements DjockeyPlugin {
+  name = "Version Directives";
+
+  constructor(public config: DjockeyConfig) {}
+
+  onPass_write(doc: DjockeyDoc) {
+    const projectVersion = this.config.projectInfo?.version;
+    applyFilter(doc.docs.content, () => ({
+      div: (node) => {
+        const keyAndValue = getAnyAttribute(
+          node,
+          Object.keys(PREFIXES_CURRENT)
+        );
+        if (!keyAndValue) return;
+        const [key, value] = keyAndValue;
+
+        // If no project version, assume it's already release. Otherwise, put it in the future.
+        const prefix =
+          !projectVersion || isSemverGreaterOrEqual(projectVersion, value)
+            ? PREFIXES_CURRENT[key as Cls]
+            : PREFIXES_FUTURE[key as Cls];
+        return buildAST(key, `${prefix} ${value}`, node.children);
+      },
+    }));
+  }
+}
+
+function buildAST(cls: string, text: string, children: Block[]): Block {
+  return {
+    tag: "div",
+    attributes: { class: `version-modified ${cls}` },
+    children: [
+      {
+        tag: "para",
+        attributes: { class: "primary" },
+        children: [{ tag: "str", text }],
+      },
+      ...structuredClone(children),
+    ],
+  };
+}
diff --git a/src/util.ts b/src/util.ts
index 18ba3b1..9edbff8 100644
--- a/src/util.ts
+++ b/src/util.ts
@@ -73,6 +73,22 @@ export function getHasClass(node: HasAttributes, cls: string): boolean {
   return values.has(cls);
 }
 
+export function getAttribute(node: HasAttributes, k: string): string | null {
+  if (!node.attributes || node.attributes[k] === undefined) return null;
+  return node.attributes[k];
+}
+
+export function getAnyAttribute(
+  node: HasAttributes,
+  keys: string[]
+): [string, string] | null {
+  if (!node.attributes) return null;
+  for (const k of keys) {
+    if (node.attributes[k] !== undefined) return [k, node.attributes[k]];
+  }
+  return null;
+}
+
 export function makeStubDjotDoc(children: Block[]): Doc {
   return {
     tag: "doc",
diff --git a/templates/html/static/dj-asides.css b/templates/html/static/dj-markupfeatures.css
similarity index 85%
rename from templates/html/static/dj-asides.css
rename to templates/html/static/dj-markupfeatures.css
index 4e3c266..423aa94 100644
--- a/templates/html/static/dj-asides.css
+++ b/templates/html/static/dj-markupfeatures.css
@@ -1,3 +1,5 @@
+/* ASIDES */
+
 aside {
   border-width: var(--aside-border-width);
   border-radius: var(--aside-border-radius);
@@ -75,3 +77,18 @@ aside.warning::before {
 aside.warning {
   border-color: var(--aside-color-border-danger);
 }
+
+/* VERSION MODIFIED */
+
+.version-modified {
+  font-style: italic;
+}
+
+.version-modified p.primary {
+  font-size: var(--fs-medium);
+  margin-bottom: 0.5em;
+}
+
+.version-modified p {
+  font-size: var(--fs-small);
+}