The purpose of this study was to examine the prevalence and correlates of religious participation among persons with co-occurring serious mental illness and type 2 diabetes. Among 201 outpatients, 53% attended religious services, 36% had regular contact with a religious leader, and 15% received assistance from a religious leader. Persons with schizophrenia and African Americans were more likely to attend services and have contact with religious leaders. Both attendance at religious services and regular contact with a religious leader were linked to higher quality of life in selected domains, but not associated with global health ratings or glycosylated hemoglobin (HbA1c) levels. Results indicate that there are important diagnostic and racial differences in religious participation, and that religious participation may be a resilience factor that supports enhanced quality of life for persons with serious mental illness and diabetes.