Background: The Veterans Health Administration (VHA) is advocating that Veterans with serious mental ill- ness (SMI) receive recovery-oriented, rehabilitation approaches that target real-world functioning. One such approach is Cognitive-Behavioral Social Skills Training (CBSST). Unlike traditional cognitive-behavioral thera- py, CBSST is a more recovery-oriented psychosocial rehabilitation intervention that teaches Veterans with SMI to correct errors in thinking and build social skills. While effective, CBSST has only been tested when facilitated by masters- or doctoral-level therapists, which limits its use in VHA. However, our pilot data shows that Peer Specialists—individuals with SMI who are hired and trained to use their own recovery experience to assist oth- ers with SMI—can also provide CBSST (called CBSST-Peer). Stand-alone social skills training (SST) is also a recovery-oriented program that VHA is attempting to rollout nationwide for Veterans with SMI. A few Peer Spe- cialists have been trained to co-lead SST with professionals. However, SST is not widely implemented be- cause professionals are busy and Peer Specialist delivered SST has not been tested. This study will evaluate the effectiveness of Peer Specialist-delivered CBSST and SST, which would increase access Veterans with SMI have to effective treatment. Our aims are: Aim 1 (Effectiveness): To compare the impact of CBSST-Peer on outcomes in Veterans with SMI to Veterans receiving Peer Specialist-delivered SST and Peer Specialist-led manualized, goal-focused groups of equal duration. We will also assess fidelity of SST and CBSST. Aim 2: (Helpfulness of CBSST/SST--Peer and implementation barriers and facilitators): To use focus groups with patients and interviews with Peer Specialists and other staff to assess perceptions of SST- and CBSST- Peer and identify potential barriers and facilitators to future implementation. Methods: This is a randomized, Hybrid 1 trial involving 252 Veterans with SMI (n=126 each from Pittsburgh, San Diego) comparing 3 treatment arms: CBSST-Peer vs. SST-Peer vs. a manualized, goal-focused group of equal duration. Hybrid 1 trials test the effectiveness of an intervention and collect implementation data that could inform its future adoption. At each site, across 6 waves (a wave = 1 CBSST-Peer, 1 SST-Peer, 1 goal focused group), 2 Peer Specialists will co-lead 18, 20-week groups. Like in the pilot, Peer Specialists will be trained and receive an hour of super- vision weekly by the CBSST developers. Master trainers from the SST rollout will train and supervise Peer Specialists in each site. All three arms' sessions will be taped and 25% rated for fidelity on standardized measures. A survey battery that assesses functioning, quality of life, recovery, and symptoms will be adminis- tered to the Veterans in each wave at: baseline, mid-intervention (10 weeks), end-of-intervention (20 weeks), and follow-up (32 weeks, 3 months post intervention). We will examine ...