diff --git a/planetstack/core/models/site.py b/planetstack/core/models/site.py
index 8a6d7c4..aee3843 100644
--- a/planetstack/core/models/site.py
+++ b/planetstack/core/models/site.py
@@ -24,11 +24,18 @@
 
     def __unicode__(self):  return u'%s' % (self.name)
 
+class SiteRole(PlCoreBase):
+
+    ROLE_CHOICES = (('admin','Admin'),('pi','PI'),('tech','Tech'),('billing','Billing'))
+    role = models.CharField(choices=ROLE_CHOICES, unique=True, max_length=30)
+
+    def __unicode__(self):  return u'%s' % (self.role)
+
 class SitePrivilege(PlCoreBase):
 
     user = models.ForeignKey('User', related_name='site_privileges')
     site = models.ForeignKey('Site', related_name='site_privileges')
-    role = models.ForeignKey('Role')
+    role = models.ForeignKey('SiteRole')
 
     def __unicode__(self):  return u'%s %s %s' % (self.site, self.user, self.role)