This observational study examined the antidepressant treatment patterns of a novel New York City methadone maintenance treatment program (MMTP), founded for the treatment of adolescents and now targeting young adults and older patients with special problems. The goal of the study was to investigate demographic or clinical characteristics that were associated with prescribing patterns, as well as whether antidepressant use was associated with sobriety. The method of data collection was a thorough chart review. Antidepressant treatment was significantly associated with gender, education, marital status, and relapse. However, after controlling for demographic and clinical characteristics, antidepressant treatment was not significantly associated with a reduction in relapse risk. Further research is needed to explore these relationships, as well as their generalizability to adult methadone clinics, and to examine the underlying factors that lead to similarities and distinctions in antidepressant prescribing practices between various types of clinics (i.e., general outpatient vs. methadone maintenance).