diff --git a/tools/check_projects_yaml_alphabetized.sh b/tools/check_projects_yaml_alphabetized.sh
new file mode 100755
index 000000000..10e5c2527
--- /dev/null
+++ b/tools/check_projects_yaml_alphabetized.sh
@@ -0,0 +1,24 @@
+#!/bin/bash -xe
+
+# Checks that reference/projects.yaml alphabetized and prints list of
+# projects that should be sorted.
+
+export TMPDIR=`/bin/mktemp -d`
+trap "rm -rf $TMPDIR" EXIT
+
+pushd $TMPDIR
+PROJECTS_LIST=$OLDPWD/reference/projects.yaml
+
+grep '^[a-zA-Z0-9]' $PROJECTS_LIST > projects_list
+
+LC_ALL=C sort --ignore-case projects_list -o projects_list.sorted
+
+if ! diff projects_list projects_list.sorted > projects_list.diff; then
+    echo "The following projects should be alphabetized: "
+    cat projects_list.diff | grep -e '> '
+    exit 1
+else
+    echo "Projects alphabetized."
+fi
+
+popd
diff --git a/tox.ini b/tox.ini
index d16e0f4c0..803d15e3c 100644
--- a/tox.ini
+++ b/tox.ini
@@ -14,3 +14,4 @@ commands = {posargs}
 
 [testenv:docs]
 commands = python setup.py build_sphinx
+            {toxinidir}/tools/check_projects_yaml_alphabetized.sh