sentences:  A large majority of self-help users use professional services as a gateway to self-help services, or concurrently with professional service or the aftercare following professional service.Professional referrals to self-help groups thus can be a cost-effective method of continuing mental health services and the two can co-exist within their own fields.While twelve-step groups, such as Alcoholics Anonymous make an indispensable contribution to the mental and/or substance use (M/SU) professional services system, a vast number of non-twelve-step groups remain underutilized within that system.