diff --git a/locale/en_US/messages.php b/locale/en_US/messages.php
index c2e89cd..4f2907e 100644
--- a/locale/en_US/messages.php
+++ b/locale/en_US/messages.php
@@ -59,6 +59,7 @@ return [
         'PERMENENT_DELETION_SUCCESSFUL'  => 'Successfully permenently deleted organisation <strong>{{name}}</strong>',
 
         'NOT_A_MEMBER'                   => 'You are not a member of organisation <strong>{{name}}</strong>.',
+        'ALREADY_IN_ONE'                 => 'You are already in an organisation.',
 
         'NAME' => [
             1 => 'Organisation name',
@@ -74,6 +75,8 @@ return [
             'REGISTER'                  => 'Register organisation',
             'SUCCESSFUL'                => 'Successfully registered organisation <strong>{{name}}</strong>',
 
+            'ALREADY_IN_ONE'            => 'You cannot register a new organisation because you are already in another organisation. (only one organisation allowed)',
+
             'CANCEL'                    => 'Cancel organisation registration',
             'CANCEL_CONFIRM'            => 'Are you sure you want to cancel the registration request for organisation <strong>{{name}}</strong>?',
             'CANCEL_YES'                => 'Yes, cancel organisation registration',
@@ -89,6 +92,8 @@ return [
         'JOIN_REQUEST' => [
             'SUBMIT_SUCCESSFUL'         => 'Request to join organisation <strong>{{name}}</strong> sent',
 
+            'ALREADY_IN_ONE'            => 'You cannot join another organisation because you are already in one (only one organisation allowed).',
+
             'REQUEST'                   => 'Request to join organisation',
 
             'CANCEL'                    => 'Cancel request to join organisation',
diff --git a/src/Controller/OrganisationMembersController.php b/src/Controller/OrganisationMembersController.php
index 92f3471..6be5c0a 100644
--- a/src/Controller/OrganisationMembersController.php
+++ b/src/Controller/OrganisationMembersController.php
@@ -80,6 +80,11 @@ class OrganisationMembersController extends SimpleController
             throw new NotFoundException();
         }
 
+        if ($config['organisation']['membership']['single_membership'] && $currentUser->organisations()->count() > 0) {
+            $ms->addMessageTranslated('danger', 'ORGANISATION.JOIN_REQUEST.ALREADY_IN_ONE');
+            return $response->withJson([], 400);
+        }
+
         // Check if the user is a member of the organisation, pending or no relation at all
         $memberCheck = $organisation->members()->where('user_id', $currentUser->id)->withPivot('flag_approved')->first();
         if ($memberCheck) {
diff --git a/src/Controller/OrganisationRegistrationController.php b/src/Controller/OrganisationRegistrationController.php
index 114f3b0..bf68815 100644
--- a/src/Controller/OrganisationRegistrationController.php
+++ b/src/Controller/OrganisationRegistrationController.php
@@ -57,24 +57,29 @@ class OrganisationRegistrationController extends SimpleController
         /** @var \UserFrosting\Sprinkle\Account\Authorize\AuthorizationManager $authorizer */
         $authorizer = $this->ci->authorizer;
 
-        /** @var \UserFrosting\Sprinkle\Account\Database\Models\Interfaces\UserInterface $currentUser */
-        $currentUser = $this->ci->currentUser;
-
-        /** @var \UserFrosting\Sprinkle\Core\Alert\AlertStream $ms */
-        $ms = $this->ci->alerts;
-
         /** @var \UserFrosting\Sprinkle\Core\Util\ClassMapper $classMapper */
         $classMapper = $this->ci->classMapper;
 
         /** @var \UserFrosting\Support\Repository\Repository $config */
         $config = $this->ci->config;
 
+        /** @var \UserFrosting\Sprinkle\Account\Database\Models\Interfaces\UserInterface $currentUser */
+        $currentUser = $this->ci->currentUser;
+
+        /** @var \UserFrosting\Sprinkle\Core\Alert\AlertStream $ms */
+        $ms = $this->ci->alerts;
+
 
         // Access-controlled page
         if (!$authorizer->checkAccess($currentUser, 'register_organisation')) {
             throw new ForbiddenException();
         }
 
+        if ($config['organisation']['membership']['single_membership'] && $currentUser->organisations()->count() > 0) {
+            $ms->addMessageTranslated('danger', 'ORGANISATION.REGISTRATION.ALREADY_IN_ONE', $data);
+            return $response->withJson([], 400);
+        }
+
         // Get POST parameters: name, slug, icon, description
         $params = $request->getParsedBody();
 
@@ -580,6 +585,9 @@ class OrganisationRegistrationController extends SimpleController
         /** @var \UserFrosting\Sprinkle\Core\Util\ClassMapper $classMapper */
         $classMapper = $this->ci->classMapper;
 
+        /** @var \UserFrosting\Support\Repository\Repository $config */
+        $config = $this->ci->config;
+
         /** @var \UserFrosting\Sprinkle\Account\Database\Models\Interfaces\UserInterface $currentUser */
         $currentUser = $this->ci->currentUser;
 
@@ -592,6 +600,10 @@ class OrganisationRegistrationController extends SimpleController
             throw new ForbiddenException();
         }
 
+        if ($config['organisation']['membership']['single_membership'] && $currentUser->organisations()->count() > 0) {
+            throw new BadRequestException();
+        }
+
         // Create a dummy organisation to prepopulate fields
         $organisation = $classMapper->createInstance('organisation', []);
 
diff --git a/templates/pages/organisations.html.twig b/templates/pages/organisations.html.twig
index 7b8efc2..de3d160 100644
--- a/templates/pages/organisations.html.twig
+++ b/templates/pages/organisations.html.twig
@@ -35,9 +35,11 @@
                         <i class="fas fa-minus-square"></i>  {{translate("VIEW_DELETED")}}
                     </button>
                 {% elseif checkAccess('register_organisation') %}
+                    {% if (organisationConfig.membership.single_membership == 0) or (current_user.organisations.count == 0) %}
                     <button type="button" class="btn btn-success js-organisation-register">
                         <i class="fas fa-plus-square"></i>  {{translate("ORGANISATION.REGISTRATION.REGISTER")}}
                     </button>
+                    {% endif %}
                 {% endif %}
                 </div>
             </div>