Through the theoretical lens of the self-presentation model, this paper addresses conflicting results from past research on the links between the components of diffidence (i.e., high levels of introversion and loneliness, and low levels of self-esteem) and alcohol use among undergraduate college students (N = 548). Correlational and multiple regression analyses were used to examine whether protective and acquisitive self-presentation expectancies about the effects of alcohol act as suppressing variables in the relationship between diffidence and alcohol use. Results supported the suppression hypothesis. A negative relationship between diffidence and alcohol use was revealed when self-presentation expectancies about the effects of alcohol were controlled statistically. The self-presentation model may provide new theoretical insights into the links between alcohol expectancies and alcohol use. Implications for campus-based intervention programs are discussed.