As the number of adults with autism spectrum disorder (ASD) grows, the need to identify modifiable correlates of positive outcomes and quality of life (QoL) gains in importance. Research indicates that perceived stress is significantly correlated with QoL in adults with ASD. Studies in the general population of individuals without disabilities indicate that greater participation in social and recreational activities may lessen the negative impact of perceived stress on well‐being, and this association may also hold among adults with ASD. We hypothesized that: (1) perceived stress would be negatively associated with QoL; and (2) higher frequency of participation in social activities and recreational activities would moderate the relationship between perceived stress and QoL. We used data collected from 60 adults with ASD aged 24–55 and their mothers to address our hypotheses. Findings indicate that adults with ASD with higher perceived stress are likely to have poorer QoL. Furthermore, greater participation in recreational activities buffers the impact of perceived stress on QoL, but no buffering effect was observed for participation in social activities. These findings suggest that interventions and services that provide supports and opportunities for participation in recreational activities may help adults with ASD manage their stress and lead to better QoL. Autism Res 2017, 10: 973–982. © 2017 International Society for Autism Research, Wiley Periodicals, Inc.