Objective: Given the proliferation of peer-delivered services and its growing but insufficient empirical base, we undertook a randomized trial to examine the effects of such services on individuals with severe psychiatric disabilities undergoing a civil commitment. Method: We recruited n = 113 individuals who were civilly committed for inpatient treatment. Randomly assigned experimental participants were paired with a trained peer specialist to receive intensive 1-on-1 support to assist them with both their recovery and the conditions of their mandated court-ordered services. Individuals in the control group were invited to receive other supportive, peer-delivered services, such as social and group educational activities, but excluding individual peer support. We assessed a variety of outcomes including social supports, quality of life, recovery, symptoms, and functioning. Results: Mounting a randomized trial in this setting and with participants who were court-ordered for inpatient treatment proved challenging in terms of recruitment, service provision, retention in the intervention, and attrition from the research. Intent-to-treat analyses revealed no significant differences in outcomes by study condition. As-treated analyses comparing high- and low-use peer support groups with control group participants found significant differences favoring peer support recipients in quality of life and functioning but no differences in other study outcomes. Conclusions and Implications for Practice: Difficulties with ensuring the quality of the peer support in this study may be in part responsible for our failure to see more-definitive and -positive results. As the peer support specialist profession evolves, an understanding of its effective ingredients and mechanisms must be elucidated to allow for more-rigorous studies.