Mental health services are required to involve family, carers, and service users in the delivery and development of mental health services but how this can be done in routine practice is challenging. One potential solution is to prescribe practice standards or clear expectation relating to family involvement. This paper describes practice standards introduced to an adult mental health service and a study that aimed to evaluate the impact of the standards on practice. Hospital and community files were audited before and after the introduction of standards for evidence of participation and surveys of carers and consumers relating to the quality of participation were undertaken. Increases in documented carer participation were found, particularly in relation to treatment or care planning. The expressed needs relating to participation varied in hospital and community settings. The majority of carers and service users were satisfied with their level of participation. The introduction of practice standards is an acceptable, inexpensive, and feasible way of improving the quality of family and carer participation, but gains may be modest.