Among young women, hookups have been found to lead to varied emotional responses. The authors tested three hypotheses to disentangle these contradictory findings in a weekly diary study. A trait-level motives hypothesis suggests that trait-level motives moderate emotional responses to hookups. A motive satisfaction hypothesis suggests that emotional responses to hooking up depend on satisfaction within hookups. A dual-effects hypothesis proposes the co-occurrence of positive and negative emotional responses. In this study, 203 college women reported trait-level motives for hooking up (e.g., pleasure/fun, intimacy, coping). Next, 5 weekly surveys asked about recent hookup experiences. These responses were compared to the same women’s emotions on weeks they did not hook up, thereby controlling for selection bias. All three hypotheses were supported. Pleasure/fun motives predicted more positive and less negative emotions; satisfaction of pleasure, intimacy, and affirmation motives resulted in more positive and less negative emotions; and simultaneous positive and negative reactions were common.