This study examined the effects of two social skills interventions, Sociodramatic Affective Relational Intervention (SDARI) and Skillstreaming, to compare their treatment mechanisms, social performance- and knowledge-training. A total of 13 youth with autism spectrum disorders were randomly assigned to 4 weeks of 1-day/week SDARI or Skillstreaming. Groups were matched on parent and child demographics, and intervention staff training. Participants were assessed on social behavior during treatment sessions, peer sociometrics, staff-reported social skills, and parent-reported social skill generalization. Results indicated that both groups increased in reciprocated friendship nominations and staff-reported social skills. Relative to Skillstreaming participants, SDARI participants liked and interacted more with each other after a single session. However, Skillstreaming participants increased in peer liking and interaction over the course of the intervention; SDARI participants decreased slightly. Parents reported no change in social functioning at home. Implications for research and practice are discussed. (Contains 2 figures and 3 tables.)