Significance to VA: The VA has made a clear commitment to implementation of peer-support programs as part of a recovery-oriented transformation of its mental health service system. However, there is currently no published research reporting the processes or outcomes of these programs. This study will provide valuable information regarding if, why and how peer support groups, as well as clinician-led recovery-oriented groups, benefit veterans with mental illness. This information will be valuable in guiding implementation of such programs across the country.