Using experience sampling methodology, we examined the effects of frequency and occurrence of appearance-based comparisons on disordered eating behaviors (binge eating, restrictive behaviors, and weight-related exercise). A total of 161 Australian women (aged 18–48) completed a baseline measure of eating pathology. An iPhone application prompted participants 6 times daily for 7 days to self-report on appearance comparisons and disordered eating behaviors since the last assessment. We hypothesized that contemporaneously reported occurrences of both upward and downward appearance comparisons, when compared to noncomparison situations, and frequency of upward comparisons would predict disordered eating behaviors. In prospective (lagged) analyses, only upward comparisons (relative to noncomparison situations) significantly predicted the likelihood of disordered eating outcomes. Trait eating pathology had a direct effect on each disordered eating variable and also moderated the influence of upward appearance comparisons (relative to noncomparison assessments) on binge-eating episodes. The lack of a differentiated effect between contemporaneously reported occurrences of upward and downward comparisons suggests that both forms of comparison increase the likelihood of disordered eating. Women may benefit from preventive programs that focus on the detrimental consequences of appearance comparisons on disordered eating; such programs may equip women with strategies to help reduce the frequency of these comparisons.