Individuals who lack a clear sense of their own identity tend to make more appearance-based comparisons and experience more body dissatisfaction, but previous research in this domain has primarily relied on cross-sectional data reflecting people's retrospective recall of their general appearance-comparison tendencies. In this study, we examined the association between trait self-concept clarity and the frequency and impact of appearance comparisons in women's everyday lives. Participants (146 women) completed a trait measure of self-concept clarity, and then participated in an ecological momentary assessment study in which they were signaled 5 times per day for 5 days and reported any appearance comparisons they made as well as their body image, affect, dieting/exercising thoughts, and dieting/exercise behavior. Self-concept clarity was negatively associated with the total number of signals at which an appearance comparison was reported, and with the number of upward (but not downward or lateral) comparisons made. However, self-concept clarity did not moderate the impact of making an appearance comparison on any of the outcomes (body image, affect, dieting/exercising thoughts, dieting/exercise behavior). These findings suggest that the increased risk associated with low self-concept clarity comes from the fact that these individuals are more frequently making (upward) appearance comparisons in their daily lives, the cumulative effects of which may result in greater body dissatisfaction over time.