diff --git a/deps.edn b/deps.edn
index 574eb8c3..930dc5b1 100644
--- a/deps.edn
+++ b/deps.edn
@@ -96,7 +96,9 @@
                          better-cond/better-cond {:mvn/version "2.1.1"}
                          org.clojure/core.specs.alpha {:mvn/version "0.2.62"}
                          reifyhealth/specmonstah {:mvn/version "2.0.0"}
-                         exoscale/coax {:mvn/version "1.0.0-alpha14"}}
+                         exoscale/coax {:mvn/version "1.0.0-alpha14"}
+                         orchestra/orchestra {:mvn/version "2021.01.01-1"}
+                         expound/expound {:mvn/version "0.8.10"}}
             :classpath-overrides {org.clojure/clojure nil
                                   org.clojure/spec.alpha nil}}
            :clj-nvd
diff --git a/test-resources/lib_tests/babashka/run_all_libtests.clj b/test-resources/lib_tests/babashka/run_all_libtests.clj
index f3fb075e..436630cf 100644
--- a/test-resources/lib_tests/babashka/run_all_libtests.clj
+++ b/test-resources/lib_tests/babashka/run_all_libtests.clj
@@ -268,6 +268,8 @@
 (test-namespaces 'better-cond.core-test)
 
 (test-namespaces 'exoscale.coax-test)
+
+(test-namespaces 'orchestra.core-test 'orchestra.expound-test 'orchestra.many-fns 'orchestra.reload-test)
 ;; TODO, after @cldwalker finishes PR to specmonstah (test-namespaces 'reifyhealth.specmonstah.core-test)
 
 ;;;; final exit code
diff --git a/test-resources/lib_tests/orchestra/core_test.cljc b/test-resources/lib_tests/orchestra/core_test.cljc
new file mode 100644
index 00000000..bbadca78
--- /dev/null
+++ b/test-resources/lib_tests/orchestra/core_test.cljc
@@ -0,0 +1,258 @@
+(ns orchestra.core-test
+  (:require #?@(:clj [[clojure.test :refer :all]
+                      [clojure.spec.alpha :as s]
+                      [clojure.spec.test.alpha :as cst]
+                      [orchestra.spec.test :as st]
+                      [orchestra.core :refer [defn-spec]]]
+
+              :cljs [[cljs.test
+                      :refer-macros [deftest testing is use-fixtures]]
+                     [cljs.spec.alpha :as s]
+                     [cljs.spec.test.alpha :as cst]
+                     [orchestra-cljs.spec.test :as st]
+                     [orchestra.core :refer-macros [defn-spec]]])))
+
+(defn-spec args' true?
+  [meow string?]
+  true)
+
+(deftest args
+  (testing "Positive"
+    (is (args' "meow")))
+  (testing "Negative"
+    (is (thrown? #?(:clj RuntimeException :cljs :default)
+                 (args' 42)))))
+
+(defn-spec ret' integer?
+  [meow any?]
+  meow)
+
+(deftest ret
+  (testing "Positive"
+    (is (= 42 (ret' 42))))
+  (testing "Negative"
+    (is (thrown? #?(:clj RuntimeException :cljs :default)
+                 (ret' true)))))
+
+(defn-spec func' number?
+  {:fn #(= (:ret %) (-> % :args :meow))}
+  [meow number?]
+  (Math/abs meow))
+
+(deftest func
+  (testing "Positive"
+    (is (= 42 (func' 42))))
+  (testing "Negative"
+    (is (thrown? #?(:clj RuntimeException :cljs :default)
+                 (func' -42)))))
+
+(defn-spec full' number?
+  {:fn #(let [meow (-> % :args :meow)
+              ret (:ret %)]
+          (or (= ret meow)
+              (and (< meow 0)
+                   (= (- ret) meow))))}
+  [meow number?]
+  (Math/abs meow))
+
+(deftest full
+  (testing "Positive"
+    (is (full' 0))
+    (is (full' -10))))
+
+(defn-spec destruct-map' number?
+  [{:keys [a b]} (s/map-of keyword? number?)]
+  (+ a b))
+
+(deftest destruct-map
+  (testing "Positive"
+    (is (= 42 (destruct-map' {:a 30 :b 12}))))
+  (testing "Negative"
+    (is (thrown? #?(:clj RuntimeException :cljs :default)
+                 (destruct-map' nil)))))
+
+(defn-spec doc-string' nil?
+  "Doc strings also work just fine."
+  []
+  nil)
+
+(deftest doc-string
+  (testing "Invocation"
+    (is (nil? (doc-string'))))
+  (testing "Meta"
+    (is (= "Doc strings also work just fine."
+           (-> #'doc-string' meta :doc)))))
+
+(defn-spec metadata' nil?
+  "Docstring"
+  {:test-meta true}
+  []
+  nil)
+
+(deftest metadata
+  (testing "Invocation"
+    (is (nil? (metadata'))))
+  (testing "Preserves metadata"
+    (is (:test-meta (meta #'metadata')))
+    (is (= "Docstring" (-> #'metadata' meta :doc)))))
+
+                                        ; Blocked on a ClojureScript bug for now
+(defn-spec arities' number?
+  ([a number?]
+   (inc a))
+  ([a number?, b number?]
+   (+ a b))
+  ([a string?, b boolean?, c map?]
+   0))
+
+#?(:clj
+   (deftest arities
+     (testing "Arity-1 Positive"
+       (is (= 2 (arities' 1))))
+     (testing "Arity-1 Negative"
+       (is (thrown? #?(:clj RuntimeException :cljs :default)
+                    (arities' false))))
+
+     (testing "Arity-2 Positive"
+       (is (= 6 (arities' 1 5))))
+     (testing "Arity-2 Negative"
+       (is (thrown? #?(:clj RuntimeException :cljs :default)
+                    (arities' "bad" nil))))
+
+     (testing "Arity-3 Positive"
+       (is (= 0 (arities' "" true {}))))
+     (testing "Arity-3 Negative"
+       (is (thrown? #?(:clj RuntimeException :cljs :default)
+                    (arities' nil nil nil))))))
+
+(defn-spec sum' number?
+  ([a number?]
+   a)
+  ; Varargs are also supported.
+  ([a number?, b number?, & args (s/* number?)]
+   (apply + a b args)))
+
+#?(:clj (deftest sum
+          (testing "Arity-1 Positive"
+            (is (= 5 (sum' 5))))
+          (testing "Arity-1 Negative"
+            (is (thrown? #?(:clj RuntimeException :cljs :default)
+                         (sum' nil))))
+
+          (testing "Arity-n Positive"
+            (is (= 25 (apply sum' (repeat 5 5)))))
+          (testing "Arity-n Negative"
+            (is (thrown? #?(:clj RuntimeException :cljs :default)
+                         (apply sum' (repeat 5 :not-a-number)))))))
+
+(defn-spec wrap-single-arity' nil?
+  ([]
+   nil))
+
+(deftest wrap-single-arity
+  (testing "Positive"
+    (is (nil? (wrap-single-arity')))))
+
+(s/def ::cat-arg (s/cat :first keyword? :rest (s/* any?)))
+(defn-spec cat-arg nil?
+  [a ::cat-arg]
+  nil)
+(defn-spec cat-args nil?
+  [a ::cat-arg, & args (s/* any?)]
+  nil)
+
+(deftest wrap-args-in-spec
+  (testing "Non-vararg Positive"
+    (is (nil? (cat-arg [:ok]))))
+  (testing "Non-vararg Negative"
+    (is (thrown? #?(:clj RuntimeException :cljs :default)
+                 (cat-arg 1))))
+  (testing "Vararg Positive"
+    (is (nil? (cat-args [:ok :anything "goes" 'here 12]))))
+  (testing "Vararg Negative Int"
+    (is (thrown? #?(:clj RuntimeException :cljs :default)
+                 (cat-args 1))))
+  (testing "Vararg Negative Seq"
+    (is (thrown? #?(:clj RuntimeException :cljs :default)
+                 (cat-args ["not a keyword" :the-rest 'does-not-matter 1.2])))))
+
+(defn empty-spec'
+  [meow]
+  (Math/abs meow))
+(s/fdef empty')
+
+(deftest empty-spec
+  (testing "Positive"
+    (is (empty-spec' 0))))
+
+(defn func-no-args-spec
+  [meow]
+  (Math/abs meow))
+(s/fdef func-no-args-spec
+        :fn #(= (:ret %) (-> % :args :meow)))
+
+(deftest func-negative
+  (testing "Negative"
+    (is (thrown? #?(:clj RuntimeException :cljs :default)
+                 (func-no-args-spec -42)))))
+
+(deftest disabled
+  (testing "Positive"
+    (cst/with-instrument-disabled
+      (is (func-no-args-spec -42)))))
+
+(defn-spec conform-ret-into-fn (s/or :error #{:error}
+                                     :success string?)
+  {:fn #(condp = (-> % :ret key)
+          :success (and (clojure.string/starts-with? (-> % :ret val)
+                                                     "your-")
+                        (clojure.string/ends-with? (-> % :ret val)
+                                                   (-> % :args :string)))
+          true)}
+  [string string?]
+  (str "your-" string))
+
+(deftest conform-ret-into-fn-test
+  (is (conform-ret-into-fn "Hello")))
+
+(defn-spec var-is-added' nil?
+  []
+  :not-nil)
+
+(deftest var-is-added
+  (testing "Positive"
+    (try
+      (var-is-added')
+      (is false "Exception should've been thrown")
+      (catch #?(:clj RuntimeException :cljs :default) ex
+        (is (= `var-is-added' (-> ex ex-data ::s/fn)))))))
+
+(defn-spec arities-work-fine' integer?
+  ([]
+   0)
+  ([i integer?]
+   i))
+
+(deftest arities-work-fine
+  (testing "Positive"
+    (is (= 0 (arities-work-fine')))
+    (is (= 777 (arities-work-fine' 777)))))
+
+(defn-spec keyword-args-work-fine' vector?
+  [& {:keys [a b]} (s/keys* :req-un [::a ::b])]
+  [a b])
+
+(deftest keyword-args-work-fine
+  (testing "Positive"
+    (is (= [1 2] (keyword-args-work-fine' :a 1 :b 2)))
+    (is (= [1 2] (keyword-args-work-fine' :b 2 :a 1))))
+
+  (testing "Negative"
+    (is (thrown? #?(:clj RuntimeException :cljs :default) (keyword-args-work-fine' :b 2)))))
+
+(defn-spec instrument-fixture any?
+  [f fn?]
+  (st/unstrument)
+  (st/instrument)
+  (f))
+(use-fixtures :each instrument-fixture)
diff --git a/test-resources/lib_tests/orchestra/expound_test.cljc b/test-resources/lib_tests/orchestra/expound_test.cljc
new file mode 100644
index 00000000..380af22e
--- /dev/null
+++ b/test-resources/lib_tests/orchestra/expound_test.cljc
@@ -0,0 +1,35 @@
+(ns orchestra.expound-test
+  (:require #?@(:clj [[clojure.test :refer :all]
+                      [clojure.spec.alpha :as s]
+                      [orchestra.spec.test :as st]
+                      [orchestra.core :refer [defn-spec]]]
+
+              :cljs [[cljs.test
+                      :refer-macros [deftest testing is use-fixtures]]
+                     [cljs.spec.alpha :as s]
+                     [orchestra-cljs.spec.test :as st]
+                     [orchestra.core :refer-macros [defn-spec]]])
+
+            [expound.alpha :as expound]))
+
+(defn-spec instrument-fixture any?
+  [f fn?]
+  (st/unstrument)
+  (st/instrument)
+  (binding [s/*explain-out* expound/printer]
+    (f)))
+(use-fixtures :each instrument-fixture)
+
+(defn-spec expound' true?
+  [blah string?]
+  true)
+
+(deftest expound
+  (testing "Pretty printed"
+    (try
+      (expound' 42)
+      (catch #?(:clj RuntimeException :cljs :default) e
+        (is (some? (-> (ex-data e)
+                       s/explain-out
+                       with-out-str
+                       (clojure.string/includes? "-- Spec failed --"))))))))
diff --git a/test-resources/lib_tests/orchestra/make_fns.cljc b/test-resources/lib_tests/orchestra/make_fns.cljc
new file mode 100644
index 00000000..c71be185
--- /dev/null
+++ b/test-resources/lib_tests/orchestra/make_fns.cljc
@@ -0,0 +1,15 @@
+(ns orchestra.make-fns
+  (:require #?@(:clj [[clojure.spec.alpha :as s]]
+                :cljs [[cljs.spec.alpha :as s]])))
+
+#?(:clj (defmacro make-fns [fn-count]
+          (let [cljs? (-> &env :ns some?)]
+            `(do
+               ~@(for [i (range fn-count)]
+                   (let [fn-name (symbol (str "fn-" i))]
+                     `(do
+                        (defn ~fn-name []
+                          (str ~fn-name))
+                        (~(if cljs?
+                            'cljs.spec.alpha/fdef
+                            's/fdef) ~fn-name))))))))
diff --git a/test-resources/lib_tests/orchestra/many_fns.cljc b/test-resources/lib_tests/orchestra/many_fns.cljc
new file mode 100644
index 00000000..1bcfc8b3
--- /dev/null
+++ b/test-resources/lib_tests/orchestra/many_fns.cljc
@@ -0,0 +1,18 @@
+(ns orchestra.many-fns
+  (:require #?@(:clj [[clojure.test :refer :all]
+                      [clojure.spec.alpha :as s]
+                      [orchestra.spec.test :as st]
+                      [orchestra.core :refer [defn-spec]]
+                      [orchestra.make-fns :refer [make-fns]]]
+
+              :cljs [[cljs.test
+                      :refer-macros [deftest testing is use-fixtures]]
+                     [cljs.spec.alpha :as s]
+                     [orchestra-cljs.spec.test :as st]
+                     [orchestra.core :refer-macros [defn-spec]]
+                     [orchestra.make-fns :refer-macros [make-fns]]])))
+
+(make-fns 2000)
+
+(deftest many-fns
+  (st/instrument))
diff --git a/test-resources/lib_tests/orchestra/reload_test.cljc b/test-resources/lib_tests/orchestra/reload_test.cljc
new file mode 100644
index 00000000..a6551532
--- /dev/null
+++ b/test-resources/lib_tests/orchestra/reload_test.cljc
@@ -0,0 +1,9 @@
+(ns orchestra.reload-test
+  (:require [clojure.test :refer :all]
+            [clojure.spec.alpha :as s]
+            [orchestra.spec.test :refer :all]))
+
+(deftest in-place-reload
+  (testing "Positive"
+    (dotimes [_ 5]
+      (require 'orchestra.spec.test :reload-all))))