diff --git a/docs/configuring-captcha.md b/docs/configuring-captcha.md
new file mode 100644
index 000000000..d137cf99e
--- /dev/null
+++ b/docs/configuring-captcha.md
@@ -0,0 +1,23 @@
+(Adapted from the [upstream project](https://github.com/matrix-org/synapse/blob/develop/docs/CAPTCHA_SETUP.md))
+
+# Overview
+Captcha can be enabled for this home server. This file explains how to do that.
+The captcha mechanism used is Google's [ReCaptcha](https://www.google.com/recaptcha/). This requires API keys from Google.
+
+## Getting keys
+
+Requires a site/secret key pair from:
+
+<http://www.google.com/recaptcha/admin>
+
+Must be a reCAPTCHA **v2** key using the "I'm not a robot" Checkbox option
+
+## Setting ReCaptcha Keys
+
+Once registered as above, set the following values:
+
+```yaml
+matrix_synapse_enable_registration_captcha: true
+matrix_synapse_recaptcha_public_key: 'YOUR_SITE_KEY'
+matrix_synapse_recaptcha_private_key: 'YOUR_SECRET_KEY'
+```
diff --git a/docs/configuring-playbook-ma1sd.md b/docs/configuring-playbook-ma1sd.md
index 03d1ecded..06a5a5b97 100644
--- a/docs/configuring-playbook-ma1sd.md
+++ b/docs/configuring-playbook-ma1sd.md
@@ -31,6 +31,8 @@ To use the [Registration](https://github.com/ma1uta/ma1sd/blob/master/docs/featu
 
 - `matrix_synapse_enable_registration` - to enable user-initiated registration in Synapse
 
+- `matrix_synapse_enable_registration_captcha` - to validate registering users using reCAPTCHA, as described in the [enabling reCAPTCHA](configuring_captcha.md) documentation.
+
 - `matrix_synapse_registrations_require_3pid` - to control the types of 3pid (`'email'`, `'msisdn'`) required by the Synapse server for registering
 
 - variables prefixed with `matrix_nginx_proxy_proxy_matrix_3pid_registration_` (e.g. `matrix_nginx_proxy_proxy_matrix_3pid_registration_enabled`) - to configure the integrated nginx webserver to send registration requests to ma1sd (instead of Synapse), so it can apply its additional functionality
diff --git a/roles/matrix-synapse/defaults/main.yml b/roles/matrix-synapse/defaults/main.yml
index d9b5b61d4..ee38b1790 100644
--- a/roles/matrix-synapse/defaults/main.yml
+++ b/roles/matrix-synapse/defaults/main.yml
@@ -162,6 +162,11 @@ matrix_synapse_allow_public_rooms_over_federation: false
 # Controls whether people with access to the homeserver can register by themselves.
 matrix_synapse_enable_registration: false
 
+# reCAPTCHA API for validating registration attempts
+matrix_synapse_enable_registration_captcha: false
+matrix_synapse_recaptcha_public_key: ''
+matrix_synapse_recaptcha_private_key: ''
+
 # Allows non-server-admin users to create groups on this server
 matrix_synapse_enable_group_creation: false
 
diff --git a/roles/matrix-synapse/templates/synapse/homeserver.yaml.j2 b/roles/matrix-synapse/templates/synapse/homeserver.yaml.j2
index 93cf43960..a02eb48fe 100644
--- a/roles/matrix-synapse/templates/synapse/homeserver.yaml.j2
+++ b/roles/matrix-synapse/templates/synapse/homeserver.yaml.j2
@@ -934,18 +934,18 @@ url_preview_accept_language:
 # This homeserver's ReCAPTCHA public key. Must be specified if
 # enable_registration_captcha is enabled.
 #
-#recaptcha_public_key: "YOUR_PUBLIC_KEY"
+recaptcha_public_key: {{ matrix_synapse_recaptcha_public_key|to_json }}
 
 # This homeserver's ReCAPTCHA private key. Must be specified if
 # enable_registration_captcha is enabled.
 #
-#recaptcha_private_key: "YOUR_PRIVATE_KEY"
+recaptcha_private_key: {{ matrix_synapse_recaptcha_private_key|to_json }}
 
 # Uncomment to enable ReCaptcha checks when registering, preventing signup
 # unless a captcha is answered. Requires a valid ReCaptcha
 # public/private key. Defaults to 'false'.
 #
-#enable_registration_captcha: true
+enable_registration_captcha: {{ matrix_synapse_enable_registration_captcha|to_json }}
 
 # The API endpoint to use for verifying m.login.recaptcha responses.
 # Defaults to "https://www.recaptcha.net/recaptcha/api/siteverify".