Methods and systems for QoS based Web filtering are described. A network access control device either permits or denies access to a web site. The network access control device also contains a mapping table which maps filtering categories to differentiated services values. When a web request is received by the network access control device, a query is sent to a web filtering server. The web filtering server returns a filtering category to the network access control device. The filtering category is mapped to a corresponding differentiated services value. The network access control device grants access privileges to the web request based on the differentiated services value.