This research examined the effects of naturally occurring appearance-focused social comparisons on women's affect, body satisfaction, and weight-related cognitions. During their daily activities, women reporting body dissatisfaction (n = 53) and women reporting body satisfaction (n = 34) recorded their reactions to comparison information. Body-dissatisfied women engaged in more comparisons and a greater proportion of upward comparisons than body-satisfied women. Upward comparisons were associated with an increase in negative affect, body dissatisfaction, and thoughts of exercising for both groups; however, body-dissatisfied women experienced a greater increase in thoughts of dieting following upward comparisons. The daily effects of comparison information on body-dissatisfied women were examined; upward comparisons were associated with increases in daily negative affect, body dissatisfaction, and weight-related cognitions.