Mental health treatment adherence is often required for offenders with mental illness supervised on probation and parole. However, research on offenders with mental illness has largely overlooked cultural and ethnic responsivity factors that may affect adherence to treatment. Latinos are a quickly growing subgroup of offenders whose social networks differ in meaningful ways from European Americans’ (e.g., size, composition, centrality of family). Social networks are known to relate to both clinical and criminal justice outcomes for offenders with mental illness, and there are features of nonoffender Latinos’ social networks that suggest that findings distilled from work with non-Latino offenders may not apply to them. The present study examined the social networks of 86 Latino probationers with serious mental illness to (a) describe the size and composition of these networks and (b) to determine which factors of social networks are related to treatment adherence. The authors found that Latino offenders’ social networks are small (∼6 individuals), consisting primarily of family and professionals such as treatment providers and probation officers. Supportive relationships with nonprofessionals and treatment providers was related to lower likelihood of missing treatment appointments, whereas social control and pressure from family and friends to attend treatment was not related to treatment adherence. Findings are discussed within the context of improved practices for community corrections and mental health agencies in working with Latino offenders with mental illness.