OBJECTIVES: We examined associations between partner types (categorized as main, casual, or commercial) and sexual risk behaviors of sexually active male-to-female (transgender female) youths. METHODS: We interviewed 120 transgender female youths aged 15 to 24 years recruited from clinics, community-based agencies, club and bar venues, referrals, and the streets of Los Angeles, California, and Chicago, Illinois. RESULTS: Sexual risk behaviors varied by partner type. Transgender female youths were less likely to use condoms during receptive anal intercourse with their main partner and were less likely to use condoms with a main partner while under the influence of substances. Youth participants were also more likely to talk to a main partner about their HIV status. Our data identified no demographic or social factors that predicted condom use during receptive anal intercourse by partner type. CONCLUSIONS: Research and interventions that focus on understanding and mitigating risk behaviors by partner type, especially those that tackle the unique risks incurred with main partners, may make important contributions to risk reduction among transgender female youths.