Appropriate and timely aftercare services are considered critical for children and adolescents with previous psychiatric hospitalization. The purpose of the present study was to investigate the relationship between type and amount of aftercare received and rehospitalization among youths who have been previously hospitalized due to psychiatric illness. The sample consisted of 569 youth ages 6–18 who received services in a large public service system. The sample of youth was 58% female and consisted largely of ethnic minorities (51% Hispanic, 26% White, 16% African American, and 7% were another race/ethnicity). Demographic, diagnostic, and service use data was obtained from billing records. Time-dependent Cox regression models evaluated the impact of aftercare (the primary dependent variable of interest) on risk of rehospitalization. Separate models were analyzed for each type of service and all models were adjusted for race/ethnicity, age, gender, diagnosis, insurance status, and comorbid substance use. Seventy percent of youths with a psychiatric hospitalization received aftercare and 28% were rehospitalized within 6 months of discharge. The total hours of services youths received was significantly related to a smaller likelihood of rehospitalization. Having a diagnosis of schizophrenia was associated with a higher risk of rehospitalization and receiving more days of day treatment was associated with a lower risk of rehospitalization. Given the restrictiveness and cost of hospitalization, mental health practitioners should focus on improving access, engagement, and quality of aftercare services.