A growing trend in mental health systems is for individuals with mental illness and experience with mental health services to work as Peer Specialists. In this role, they serve as role models and provide support, education and advocacy to clients using mental health services. The authors recently completed an evaluation of a training program that prepares Peer Specialists for this work in the Massachusetts mental health delivery system. Using a mixed methods approach, the evaluation explored a) strengths and opportunities to enhance the training program and b) the degree to which the training program is establishing a competent workforce of certified peer specialists throughout Massachusetts. This paper will describe the overall evaluation aims and questions, rationale for using a mixed methods approach, and details of the study design. It will also present integrated findings regarding the training’s impact on its participants and a description of factors that explain this impact. #2010Conference #Alcohol,DrugAbuse,andMentalHealth