Youth with autism spectrum disorder can face social-communication challenges related to sexuality, dating, and friendships. The purpose of this study was to assess the feasibility, acceptability, and preliminary efficacy of the Supporting Teens with Autism on Relationships program. In total, 84 youth with autism spectrum disorder aged 9 to 18 and their parents participated in this study; two groups received the Supporting Teens with Autism on Relationships program (interventionist-led parent group vs parent self-guided), while an attentional control group received a substance abuse prevention program that included instruction in problem-solving and social skills. Feasibility and acceptability of the Supporting Teens with Autism on Relationships program was high overall. The Supporting Teens with Autism on Relationships program was effective in increasing parent and youth knowledge of sexuality, while the attentional control was not. There was preliminary support for improvement in parenting efficacy related to discussing sexuality with their children. Gains were seen among completers regardless of whether the parent received support from a facilitator. Implications and future directions are discussed.