•An experiment tested the effect of Facebook use on women's mood and body image.•Exposure to Facebook (relative to a control website) resulted in more negative mood.•For women high in appearance comparison, Facebook usage led to more facial discrepancy. The present study experimentally investigated the effect of Facebook usage on women's mood and body image, whether these effects differ from an online fashion magazine, and whether appearance comparison tendency moderates any of these effects. Female participants (N=112) were randomly assigned to spend 10min browsing their Facebook account, a magazine website, or an appearance-neutral control website before completing state measures of mood, body dissatisfaction, and appearance discrepancies (weight-related, and face, hair, and skin-related). Participants also completed a trait measure of appearance comparison tendency. Participants who spent time on Facebook reported being in a more negative mood than those who spent time on the control website. Furthermore, women high in appearance comparison tendency reported more facial, hair, and skin-related discrepancies after Facebook exposure than exposure to the control website. Given its popularity, more research is needed to better understand the impact that Facebook has on appearance concerns.