Social anxiety symptoms are common among cognitively unimpaired youth with autism spectrum disorder (ASD). Few studies have investigated the co-occurrence of social anxiety disorder (SAD) in adults with ASD, although identification may aid access to effective treatments and inform our scientific efforts to parse heterogeneity. In this preliminary study, we examined the clinical presentation of SAD in adults with ASD (n = 28), relative to SAD uncomplicated by ASD (n = 26). A large subset (50%) of the adults with ASD met diagnostic criteria for SAD. The adults with ASD plus SAD differed from those with ASD without SAD on several characteristics. Findings demonstrate that many adults with ASD are aware of their social difficulties and experience impairing social anxiety.