College represents a unique vulnerability period for the development of body dissatisfaction and disordered eating among women. These negative health concerns may be at least partially explained by social comparison and objectification theories. This study extended previous research by examining how these theories fit into an elaborated version of the sociocultural model of disordered eating and by using an ecological momentary assessment (EMA) approach. Participants were 238 women attending a large, public Southeastern university. They completed two self-report questionnaire sessions (at the start and end of an academic semester) and a two-week EMA component (i.e., via their personal computers, participants completed a short set of questions 3x/day mid-semester). First, eating disorder-related social comparison (i.e., including body, eating, and exercise comparisons) and body surveillance (i.e., the behavioral indicator of self-objectification) were tested as factors that may explain the relation between thin ideal internalization and body dissatisfaction in the sociocultural model of disordered eating. Results indicated that this model provided a good fit to the data and that the total indirect effect from thin ideal internalization to body dissatisfaction through this set of mediators was significant. Social comparison emerged as a significant specific mediator while body surveillance did not. This mediation model did not hold prospectively. Second, we examined the effects of momentary body, eating, and exercise social comparisons and body surveillance on momentary body dissatisfaction. When examining these effects in a single model, results indicated that within- and between-person levels of body comparisons and body surveillance, within-person levels of eating comparisons, and within-person levels of exercise comparisons predicted increased body dissatisfaction contemporaneously. Between-person levels of eating and exercise comparisons did not predict unique variance in body dissatisfaction. Finally, we were interested in whether trait thin ideal internalization predicted momentary reports of body dissatisfaction and if this relationship was mediated by momentary reports of body, eating, and exercise social comparison and body surveillance. Although the total between-person indirect effect through this set of mediators was significant, only body comparison and body surveillance emerged as significant specific mediators. These findings have significant clinical implications and are suggestive of many avenues for future research.