diff --git a/Gemfile b/Gemfile
index b06cf0c25..19e7f2d5e 100644
--- a/Gemfile
+++ b/Gemfile
@@ -3,6 +3,7 @@ git_source(:bc) { |repo| "https://github.com/basecamp/#{repo}" }
 ruby file: ".ruby-version"
 
 gem "rails", github: "rails/rails", branch: "main"
+gem "active_record-tenanted", bc: "active_record-tenanted"
 
 # Assets & front end
 gem "importmap-rails"
diff --git a/Gemfile.lock b/Gemfile.lock
index 7d8fd4fac..b8f20d2bc 100644
--- a/Gemfile.lock
+++ b/Gemfile.lock
@@ -1,3 +1,13 @@
+GIT
+  remote: https://github.com/basecamp/active_record-tenanted
+  revision: ac50c284049388344ba2603eae114e34fcf6bce0
+  specs:
+    active_record-tenanted (0.1.0)
+      activerecord (>= 8.1.alpha)
+      rack-contrib (>= 2.5.0)
+      railties (>= 8.1.alpha)
+      zeitwerk
+
 GIT
   remote: https://github.com/basecamp/rails-structured-logging
   revision: 0c2d45dd98c92156cc419e75cdad2aa903290d82
@@ -268,6 +278,8 @@ GEM
     raabro (1.4.0)
     racc (1.8.1)
     rack (3.1.11)
+    rack-contrib (2.5.0)
+      rack (< 4)
     rack-session (2.1.0)
       base64 (>= 0.1.0)
       rack (>= 3.0.0)
@@ -420,6 +432,7 @@ PLATFORMS
   x86_64-linux-musl
 
 DEPENDENCIES
+  active_record-tenanted!
   bcrypt (~> 3.1.7)
   bootsnap
   brakeman