Generalist mental health practitioners are likely to encounter patients with substance use disorders, indicating community-based, 12-Step mutual-help organizations (MHOs) can be a valuable referral source for these clinicians. Little is known, however, about how generalist practitioners and trainees understand these organizations. Results of a survey among 316 clinical trainees showed that knowledge levels were below a competency benchmark. While views were positive overall, empirically-inconsistent beliefs were also common. Beliefs and attitudes accounted for approximately one half of the variance in professional intentions (e.g., appropriate referral). The study highlighted knowledge gaps, though trainees appeared open to learning more about 12-Step MHOs. Thus systematic development and evaluation of clinical training in the area may be warranted.