The present study aimed to investigate the role of social comparison processing in women's responses to thin idealized images. In particular, it was predicted that comparison with the images on the basis of appearance would lead to more negative outcomes than comparison on the basis of intelligence. A sample of 114 women viewed fashion magazine advertisements featuring thin and attractive models under one of three instructional set conditions: control, appearance comparison, and intelligence comparison instructions. We found that both comparison instructional set conditions led to decreased mood relative to the control condition, but they had no effect on subsequent body dissatisfaction. However, regression analyses indicated that the form of processing in which individuals (irrespective of experimental condition) actually engaged was crucial. In particular, both appearance comparison processing (positively) and intelligence comparison processing (negatively) were associated with increased body dissatisfaction. In addition, poorer recall of both products and their brand names was associated with a greater impact of the media images on mood and body dissatisfaction. We concluded that the dimensions on which social comparison takes place are critical in women's response to media-portrayed thin ideal images, with comparisons on the basis of intelligence or education associated with more positive reactions. More generally, the results offer strong support to appearance social comparison as the mechanism by which idealized media images translate into body dissatisfaction for many women. (Contains 3 tables.)