diff --git a/.travis.yml b/.travis.yml
index 0dbd6b61c..97dd3d55a 100644
--- a/.travis.yml
+++ b/.travis.yml
@@ -4,5 +4,9 @@ python:
 install:
   - pip install --upgrade .
   - pip install pylint
+  - pip install python-coveralls
 script:
   - ./run_presubmit.sh
+after_success:
+  # Upload coverage data to coveralls.io.
+  - coveralls
diff --git a/README.md b/README.md
index 0381fa173..49ba47a53 100644
--- a/README.md
+++ b/README.md
@@ -1,7 +1,8 @@
 # GCP Variant Transforms
 
 [![Build Status](https://travis-ci.org/googlegenomics/gcp-variant-transforms.svg?branch=master)](https://travis-ci.org/googlegenomics/gcp-variant-transforms)
-
+[![Coverage
+Status](https://coveralls.io/repos/github/googlegenomics/gcp-variant-transforms/badge.svg)](https://coveralls.io/github/googlegenomics/gcp-variant-transforms)
 
 ## Overview
 
diff --git a/run_presubmit.sh b/run_presubmit.sh
index 64a4bb445..86623e2ec 100755
--- a/run_presubmit.sh
+++ b/run_presubmit.sh
@@ -18,7 +18,7 @@ set -euo pipefail
 # A helper script for ensuring all checks pass before submitting any change.
 
 echo ========== Running unit tests.
-python setup.py test
+coverage run --source=gcp_variant_transforms setup.py test
 
 echo ========== Running pylint.
 pylint gcp_variant_transforms