The authors assessed the association of 2 personality dimensions with use and abuse of alcohol in 1,320 twin pairs concordantly reporting nonabstinence at age 18.5 years. The 2 alcohol outcomes differentially relate to the 2 personality dimensions: Alcohol-related problems correlate more highly with social deviance than with excitement seeking (ES), and alcohol consumption correlates more highly with ES than with social deviance. Biometric models fit to the data identified similar patterns in genetic covariance, although differences were more evident in genetic correlations between social deviance and alcohol outcomes than in those for ES. Results suggest that genetic influences underlie the association of personality with alcohol use and subsequent problems and illustrate the utility of informative twin analyses in exploring links between genes, personality, and behavior disorder.