diff --git a/activitypub-servist.asd b/activitypub-servist.asd
index 9848eb3..f364aad 100644
--- a/activitypub-servist.asd
+++ b/activitypub-servist.asd
@@ -14,6 +14,17 @@
   :components ((:file "src/activitypub-servist")))
 
 
+(asdf:defsystem "activitypub-servist/activity-vocabulary"
+  :version "0.0"
+  :license "AGPLv3"
+  :description "AP-S subpackage for handling ActivityVocabulary parsing/encoding."
+  :author "Jaidyn Ann <jadedctrl@posteo.at>"
+  :homepage "https://hak.xwx.moe/jadedctrl/activitypub-servist"
+
+  :depends-on ("alexandria" "closer-mop" "str" "yason")
+  :components ((:file "src/activity-vocabulary")))
+
+
 (asdf:defsystem "activitypub-servist/signatures"
   :version "0.0"
   :license "AGPLv3"
@@ -28,6 +39,16 @@
 
 ;;; Tests
 ;;; —————————————————————————————————————
+(asdf:defsystem "activitypub-servist/tests/activity-vocabulary"
+  :version "0.0"
+  :license "AGPLv3"
+  :author "Jaidyn Ann <jadedctrl@posteo.at>"
+  :description "Tests for the the activitypub-servist/signatures package."
+
+  :depends-on (:activitypub-servist/activity-vocabulary :alexandria :lisp-unit2)
+  :components ((:file "t/activity-vocabulary")))
+
+
 (asdf:defsystem "activitypub-servist/tests/signatures"
   :version "0.0"
   :license "AGPLv3"
@@ -37,10 +58,11 @@
   :depends-on (:activitypub-servist/signatures :lisp-unit2)
   :components ((:file "t/signatures")))
 
+
 ;; Following method tweaked from lisp-unit2’s documentation:
 ;; https://github.com/AccelerationNet/lisp-unit2/blob/master/README.md#asdf
-(defmethod asdf:perform
-    ((o asdf:test-op) (c (eql (asdf:find-system :activitypub-servist/tests/signatures))))
-  (eval (read-from-string
-         "(lisp-unit2:with-summary ()
-            (lisp-unit2:run-tests :package :activitypub-servist/tests/signatures))")))
+(defmethod asdf:perform ((o asdf:test-op) (c (eql (asdf:find-system :activitypub-servist/tests/activity-vocabulary))))
+  (eval (read-from-string "(activtiypub-servist/tests/activity-vocabulary:run)")))
+
+(defmethod asdf:perform ((o asdf:test-op) (c (eql (asdf:find-system :activitypub-servist/tests/signatures))))
+  (eval (read-from-string "(activtiypub-servist/tests/signatures:run)")))
diff --git a/t/activity-vocabulary.lisp b/t/activity-vocabulary.lisp
new file mode 100644
index 0000000..7de47d3
--- /dev/null
+++ b/t/activity-vocabulary.lisp
@@ -0,0 +1,81 @@
+;;;; activitypub-servist/tests/activity-vocabulary: Testing activity-vocabulary.
+
+;; Copyright © 2024 Jaidyn Levesque <jadedctrl@posteo.at>
+;;
+;; This program is free software: you can redistribute it and/or
+;; modify it under the terms of the GNU Affero General Public License
+;; as published by the Free Software Foundation, either version 3 of
+;; the License, or (at your option) any later version.
+;;
+;; This program is distributed in the hope that it will be useful,
+;; but WITHOUT ANY WARRANTY; without even the implied warranty of
+;; MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
+;; GNU Affero General Public License for more details.
+;;
+;; You should have received a copy of the GNU Affero General Public License
+;; along with this program. If not, see <https://www.gnu.org/licenses/>.
+
+(defpackage :activitypub-servist/tests/activity-vocabulary
+  (:use :cl :lisp-unit2)
+  (:nicknames "AP-S/T/AV")
+  (:export :run))
+
+(in-package :activitypub-servist/tests/activity-vocabulary)
+
+(defun run ()
+  "Run all ACTIVITY-VOCABULARY tests."
+  (lisp-unit2:with-summary ()
+    (lisp-unit2:run-tests :package :activitypub-servist/tests/activity-vocabulary)))
+
+
+
+;;; Util
+;;; ————————————————————————————————————————
+(defmacro relative-pathname (path)
+  "Return an absolute path adding the relative PATH to the system’s path."
+  `(asdf:system-relative-pathname :activitypub-servist/tests/activity-vocabulary ,path))
+
+(defmacro define-json-test (path tags)
+  "Define a lisp-unit2 test for parsing of the given JSON file.
+We compare the original JSON to that of the parsed-then-reserialized JSON,
+ensuring they are semantically equivalent. White-space and key order are ignored."
+  (let ((content (alexandria:read-file-into-string (relative-pathname path))))
+    `(define-test ,(intern (string-upcase (pathname-name path))) (:tags ,tags)
+       (assert-equal
+        (hash-table-sorted-alist
+         (yason:parse ,content))
+        (hash-table-sorted-alist
+         (yason:parse
+          (yason:with-output-to-string* ()
+            (yason:encode-object
+             (av:parse ,content)))))))))
+
+(defun sort-alist (alist predicate)
+  "Sort an associative list by its keys."
+  (sort alist
+        (lambda (cell-a cell-b)
+          (apply predicate (list (car cell-a) (car cell-b))))))
+
+(defun hash-table-sorted-alist (table &optional (predicate #'string<))
+  "Return a sorted associative list containing the keys and values of TABLE.
+Any nested hash-tables found as values are also sorted, recursively."
+  (sort-alist
+   (mapcar (lambda (cell)
+             (cons (car cell)
+                   (if (hash-table-p (cdr cell))
+                       (hash-table-sorted-alist (cdr cell))
+                       (cdr cell))))
+           (alexandria:hash-table-alist table))
+   predicate))
+
+
+
+;;; Test definitions
+;;; ————————————————————————————————————————
+;; Define a test for each ActivityVocabulary type’s example JSON.
+;; Examples are taken from the spec:
+;;   https://www.w3.org/TR/activitystreams-vocabulary/
+(mapcar (lambda (file)
+          (eval `(define-json-test ,file '(:core))))
+        (uiop:directory-files
+         (relative-pathname "t/activity-vocabulary/core/")))
diff --git a/t/activity-vocabulary/core/activity.json b/t/activity-vocabulary/core/activity.json
new file mode 100644
index 0000000..5b03c30
--- /dev/null
+++ b/t/activity-vocabulary/core/activity.json
@@ -0,0 +1,13 @@
+{
+	"@context": "https://www.w3.org/ns/activitystreams",
+	"type": "Activity",
+	"summary": "Sally did something to a note",
+	"actor": {
+		"type": "Person",
+		"name": "Sally"
+	},
+	"object": {
+		"type": "Note",
+		"name": "A Note"
+	}
+}
diff --git a/t/activity-vocabulary/core/collection-page.json b/t/activity-vocabulary/core/collection-page.json
new file mode 100644
index 0000000..a3abab4
--- /dev/null
+++ b/t/activity-vocabulary/core/collection-page.json
@@ -0,0 +1,17 @@
+{
+	"@context": "https://www.w3.org/ns/activitystreams",
+	"summary": "Page 1 of Sally's notes",
+	"type": "CollectionPage",
+	"id": "http://example.org/foo?page=1",
+	"partOf": "http://example.org/foo",
+	"items": [
+		{
+			"type": "Note",
+			"name": "A Simple Note"
+		},
+		{
+			"type": "Note",
+			"name": "Another Simple Note"
+		}
+	]
+}
diff --git a/t/activity-vocabulary/core/collection.json b/t/activity-vocabulary/core/collection.json
new file mode 100644
index 0000000..32a4b2d
--- /dev/null
+++ b/t/activity-vocabulary/core/collection.json
@@ -0,0 +1,16 @@
+{
+	"@context": "https://www.w3.org/ns/activitystreams",
+	"summary": "Sally's notes",
+	"type": "Collection",
+	"totalItems": 2,
+	"items": [
+		{
+			"type": "Note",
+			"name": "A Simple Note"
+		},
+		{
+			"type": "Note",
+			"name": "Another Simple Note"
+		}
+	]
+}
diff --git a/t/activity-vocabulary/core/intransitive-activity.json b/t/activity-vocabulary/core/intransitive-activity.json
new file mode 100644
index 0000000..d02cd77
--- /dev/null
+++ b/t/activity-vocabulary/core/intransitive-activity.json
@@ -0,0 +1,13 @@
+{
+	"@context": "https://www.w3.org/ns/activitystreams",
+	"type": "Travel",
+	"summary": "Sally went to work",
+	"actor": {
+		"type": "Person",
+		"name": "Sally"
+	},
+	"target": {
+		"type": "Place",
+		"name": "Work"
+	}
+}
diff --git a/t/activity-vocabulary/core/link.json b/t/activity-vocabulary/core/link.json
new file mode 100644
index 0000000..acc7490
--- /dev/null
+++ b/t/activity-vocabulary/core/link.json
@@ -0,0 +1,8 @@
+{
+	"@context": "https://www.w3.org/ns/activitystreams",
+	"type": "Link",
+	"href": "http://example.org/abc",
+	"hreflang": "en",
+	"mediaType": "text/html",
+	"name": "An example link"
+}
diff --git a/t/activity-vocabulary/core/object.json b/t/activity-vocabulary/core/object.json
new file mode 100644
index 0000000..8bd7c51
--- /dev/null
+++ b/t/activity-vocabulary/core/object.json
@@ -0,0 +1,6 @@
+{
+	"@context": "https://www.w3.org/ns/activitystreams",
+	"type": "Object",
+	"id": "http://www.test.example/object/1",
+	"name": "A Simple, non-specific object"
+}
diff --git a/t/activity-vocabulary/core/ordered-collection-page.json b/t/activity-vocabulary/core/ordered-collection-page.json
new file mode 100644
index 0000000..0e45a01
--- /dev/null
+++ b/t/activity-vocabulary/core/ordered-collection-page.json
@@ -0,0 +1,17 @@
+{
+	"@context": "https://www.w3.org/ns/activitystreams",
+	"summary": "Page 1 of Sally's notes",
+	"type": "OrderedCollectionPage",
+	"id": "http://example.org/foo?page=1",
+	"partOf": "http://example.org/foo",
+	"orderedItems": [
+		{
+			"type": "Note",
+			"name": "A Simple Note"
+		},
+		{
+			"type": "Note",
+			"name": "Another Simple Note"
+		}
+	]
+}
diff --git a/t/activity-vocabulary/core/ordered-collection.json b/t/activity-vocabulary/core/ordered-collection.json
new file mode 100644
index 0000000..a7f456a
--- /dev/null
+++ b/t/activity-vocabulary/core/ordered-collection.json
@@ -0,0 +1,16 @@
+{
+	"@context": "https://www.w3.org/ns/activitystreams",
+	"summary": "Sally's notes",
+	"type": "OrderedCollection",
+	"totalItems": 2,
+	"orderedItems": [
+		{
+			"type": "Note",
+			"name": "A Simple Note"
+		},
+		{
+			"type": "Note",
+			"name": "Another Simple Note"
+		}
+	]
+}
diff --git a/t/signatures.lisp b/t/signatures.lisp
index 6394960..cc92812 100644
--- a/t/signatures.lisp
+++ b/t/signatures.lisp
@@ -16,11 +16,21 @@
 ;; along with this program. If not, see <https://www.gnu.org/licenses/>.
 
 (defpackage :activitypub-servist/tests/signatures
-  (:use :cl :lisp-unit2))
+  (:use :cl :lisp-unit2)
+  (:nicknames "AP-S/T/S")
+  (:export :run))
 
 (in-package :activitypub-servist/tests/signatures)
 
+(defun run ()
+  "Run all SIGNATURES tests."
+  (lisp-unit2:with-summary ()
+    (lisp-unit2:run-tests :package :activitypub-servist/tests/signatures)))
 
+
+
+;;; Test definitions
+;;; ————————————————————————————————————————
 (define-test string-sha256sum (:tags '(misc))
   (assert-equal
    "erws/VxJ7XO5xQBqpwHIUwG0P4q1Ek2D4N053+E2Ib8="