diff --git a/src/co/gaiwan/compass/routes/sessions.clj b/src/co/gaiwan/compass/routes/sessions.clj
index 37cae46..5aea752 100644
--- a/src/co/gaiwan/compass/routes/sessions.clj
+++ b/src/co/gaiwan/compass/routes/sessions.clj
@@ -15,7 +15,9 @@
    [co.gaiwan.compass.model.session :as session]
    [co.gaiwan.compass.model.user :as user]
    [java-time.api :as time]
-   [co.gaiwan.compass.services.discord :as discord]))
+   [co.gaiwan.compass.services.discord :as discord]
+   [co.gaiwan.compass.util :as util]
+   [clojure.string :as str]))
 
 (defn GET-session-new [req]
   (if-not (:identity req)
@@ -171,8 +173,21 @@
         {:status 409
          :body "Session thread already exists"}
         (if (discord/create-session-thread session)
-          (do
+          (let [participant-ids
+                (db/q '[:find [?id ...]
+                        :in $ ?sid
+                        :where
+                        [?sid :session/participants ?pid]
+                        [?pid :discord/id ?id]]
+                      (db/db) session-eid)
+                notif-msgs (->> participant-ids
+                                (map discord/user-mention)
+                                (map (partial format " %s "))
+                                (util/partition-with-limit discord/message-limit)
+                                (map str/join))]
             (discord/update-session-thread-member session-eid (:discord/id identity) :add)
+            (doseq [msg notif-msgs]
+              (discord/send-session-thread-message session-eid msg))
             {:location [:session/get {:id session-eid}]
              :flash "Thread created! You should have got a notification in Discord."})
           {:status 500
diff --git a/src/co/gaiwan/compass/services/discord.clj b/src/co/gaiwan/compass/services/discord.clj
index 4bb3ae5..16274a6 100644
--- a/src/co/gaiwan/compass/services/discord.clj
+++ b/src/co/gaiwan/compass/services/discord.clj
@@ -7,6 +7,8 @@
    [io.pedestal.log :as log]
    [co.gaiwan.compass.db :as db]))
 
+(def message-limit 2000)
+
 (def discord-api-endpoint "https://discord.com/api/v10")
 
 (defn bot-auth-headers []
diff --git a/src/co/gaiwan/compass/util.clj b/src/co/gaiwan/compass/util.clj
index 4f4160c..ccea43f 100644
--- a/src/co/gaiwan/compass/util.clj
+++ b/src/co/gaiwan/compass/util.clj
@@ -84,3 +84,17 @@
 (defn expires-in->instant
   [expires-in]
   (.plusSeconds (Instant/now) (- expires-in 60)))
+
+(defn partition-with-limit
+  [limit parts]
+  (loop [result []
+         current []
+         length 0
+         [p & rest] parts]
+    (let [part-length (count p)
+          new-length (+ length part-length)]
+      (cond
+        (> part-length limit) nil
+        (nil? p) (cond-> result (seq current) (conj current))
+        (<= new-length limit) (recur result (conj current p) new-length rest)
+        :else (recur (conj result current) [] 0 (list* p rest))))))