The purpose of this study was to assess the impact of a mental illness self-management intervention, called Wellness Recovery Action Planning (WRAP), on the use of and need for mental health services over time compared with nutrition and wellness education. Participants were recruited from outpatient community mental health settings in Chicago, Illinois. Using a single-blind, randomized controlled trial design, 143 individuals were assigned to WRAP or to a nutrition education course and assessed at baseline and at 2-month and 8-month follow-up. The WRAP intervention was delivered by peers in recovery from serious mental illness who were certified WRAP educators over nine weekly sessions lasting 2.5 hrs. The nutrition education curriculum was taught by trained non-peer educators using the same schedule. Mixed-effects random regression analysis tested for differences between the two interventions in (a) self-reported use of 19 clinical, rehabilitation, peer, emergent, and ancillary services; and (b) self-reported need for these services. Results of mixed-effects random regression analysis indicated that, compared with controls, WRAP participants reported significantly greater reduction over time in service utilization (total, individual, and group), and service need (total and group services). Participants in both interventions improved significantly over time in symptoms and recovery outcomes. Training in mental illness self-management reduced the self-reported need for and use of formal mental health services over time. This confirms the importance of WRAP in an era of dwindling behavioral health service availability and access.