Research displays a link between interpersonal stress and body image during adolescence, but has yet to be considered in young adults. The present experimental study tests the effect of interpersonal stress on general and weight-specific body dissatisfaction, and the moderating effect of gender and appearance importance. N=111 university students aged between 18 and 25 years were randomly assigned to three conditions in which participants were exposed to vicarious peer rejection based on appearance or personality, and a no rejection control. Results revealed support for a causal effect of interpersonal (peer-related) stress on state body dissatisfaction, with males reporting greater general body dissatisfaction under a personality-based peer rejection condition, and an increase in weight dissatisfaction for those reporting low appearance importance under appearance-based rejection. Females reported greater body dissatisfaction regardless of the nature of interpersonal interactions. The research holds implications for prevention and early intervention programs in young adults.