Sexual assault is a significant problem for college women. The self-medication hypothesis frames post-assault alcohol use as a strategy to cope with stress and negative mood. This thesis examined how alcohol use coping motives mediate the relationship between daily fluctuations in stress and negative mood and subsequent alcohol consumption in women with sexual assault histories who are heavy drinkers. Although Bayesian multilevel models did not support the between-person mediation pathways, within-person mediation was supported for negative mood, such that increases in negative mood predicted greater alcohol use coping motives, which in turn predicted greater alcohol use. Together, these findings offer event-level evidence that negative mood operates as a proximal predictor of alcohol use via alcohol use coping motives. By demonstrating the importance of state-level negative mood as a proximal predictor of alcohol use via alcohol use coping motives, these results underscore the importance of interventions that reduce in-the-moment negative mood.