diff --git a/.gitmodules b/.gitmodules
new file mode 100644
index 0000000..b2db72a
--- /dev/null
+++ b/.gitmodules
@@ -0,0 +1,9 @@
+[submodule "friends/bowser/2021"]
+	path = friends/bowser/2021
+	url = git@github.com:jgbowser/Advent-of-Code_2021.git
+[submodule "friends/jay"]
+	path = friends/jay
+	url = git@github.com:jhannah/adventofcode.git
+[submodule "friends/eric"]
+	path = friends/eric
+	url = git@github.com:ewagoner/adventofcode2021.git
diff --git a/friends/bowser/2021 b/friends/bowser/2021
new file mode 160000
index 0000000..df75cac
--- /dev/null
+++ b/friends/bowser/2021
@@ -0,0 +1 @@
+Subproject commit df75cac820df97eb322149239bd10951abd7e828
diff --git a/friends/eric b/friends/eric
new file mode 160000
index 0000000..a85f406
--- /dev/null
+++ b/friends/eric
@@ -0,0 +1 @@
+Subproject commit a85f4063d48dd84dc366081533e2c17ee479d3d5
diff --git a/friends/jay b/friends/jay
new file mode 160000
index 0000000..3c804c7
--- /dev/null
+++ b/friends/jay
@@ -0,0 +1 @@
+Subproject commit 3c804c7354980c59df56ce3f48e6dccd34d2b819