diff --git a/README.md b/README.md
index 78cc9cb..eb802b8 100644
--- a/README.md
+++ b/README.md
@@ -24,3 +24,21 @@ test-requirements.txt:
 git+https://github.com/openstack-charmers/zaza.git#egg=zaza
 git+https://github.com/openstack-charmers/zaza-openstack-tests.git#egg=zaza.openstack
 ```
+
+## Configuration
+
+Zaza-openstack-test uses environment variables to configure the tests:
+
+| Env var                      | Description                                               | Default Value        |
+|------------------------------|-----------------------------------------------------------|----------------------|
+| `TEST_EXT_NET`               | Name of external network                                  | `ext_net`            |
+| `TEST_EXT_NET_SUBNET`        | Name of external subnet                                   | `ext_net_subnet`     |
+| `TEST_PRIVATE_NET`           | Name of private network                                   | `private`            |
+| `TEST_PRIVATE_NET_SUBNET`    | Name of private subnet                                    | `private_subnet`     |
+| `TEST_PROVIDER_ROUTER`       | Name of private-external router                           | `provider-router`    |
+| `TEST_CIRROS_IMAGE_NAME`     | Name of cirros image                                      | `cirros`             |
+| `TEST_BIONIC_IMAGE_NAME`     | Name of bionic image                                      | `bionic`             |
+| `TEST_FOCAL_IMAGE_NAME`      | Name of focal image                                       | `focal`              |
+| `TEST_JAMMY_IMAGE_NAME`      | Name of jammy image                                       | `jammy`              |
+| `TEST_PRIVKEY`               | Path to private key corresponding to `TEST_KEYPAIR_NAME`  |                      |
+| `TEST_KEYPAIR_NAME`          | Name of keypair                                           | `zaza`               |