ABSTRACT. Objective: The purpose of this study was to conduct a meta-analysis summarizing the effectiveness of brief, single-session interventions to reduce alcohol use among heavy drinking college students. Method: A comprehensive literature search identified 73 studies comparing the effects of single-session brief alcohol intervention with treatment-as-usual or no-treatment control conditions on alcohol use among heavy drinking college students. Random-effects meta-analyses with robust variance estimates were used to synthesize 662 effect sizes, estimating the average overall effect of the interventions and the variability in effects across a range of moderators. Results: An overall mean effect size of g\ = 0.18, 95% CI [0.12, 0.24] indicated that, on average, single-session brief alcohol interventions significantly reduced alcohol use among heavy drinking college students relative to comparison conditions. There was minimal variability in effects associated with study method and quality, general study characteristics, participant demographics, or outcome measure type. However, studies using motivational enhancement therapy/motivational interviewing (MET/MI) modalities reported larger effects than those using psychoeducational therapy (PET) interventions. Further investigation revealed that studies using MET/ MI and feedback-only interventions, but not those using cognitive-behavioral therapy or PET modalities, reported average effect sizes that differed significantly from zero. There was also evidence that long-term effects were weaker than short-term effects. Conclusions: Single-session brief alcohol interventions show modest effects for reducing alcohol consumption among heavy drinking college students and may be particularly effective when they incorporate MET/MI principles. More research is needed to directly compare intervention modalities, to develop more potent interventions, and to explore the persistence of long-term effects. (J. Stud. Alcohol Drugs, 76, 530-543, 2015)