Undergraduates with high social anxiety have increased alcohol problems, despite lower or equivalent alcohol use levels. Drinking motives mediate the cross-sectional relationship between social anxiety and alcohol problems, with coping and conformity motives being the most commonly observed mediators. Our study extended prior research by using a longitudinal design, examining coping with anxiety motives (CAM) and coping with depression motives (CDM) separately using path analysis, simultaneously considering a variety of drinking motives in the model, and focusing on a particularly severe form of social anxiety – namely, social avoidance. We collected data from 219 undergraduates (72.6% women, mean age of 20.59 years) over three waves spaced six months apart. Results indicated CDM mediated the prospective relationship between social avoidance and alcohol problems. Findings suggest socially avoidant students’ escalations in CDM explain their increased alcohol problems over time. Future research should examine involvement of depression and social isolation in contributing to this pathway to alcohol problems.