Objective: The aim of this study was to examine the relationships between body mass index (BMI) and alcohol use and misuse in young adulthood in a sample of black and white female twins. Method: Cox proportional hazards and logistic regression models were used to examine the relationships between BMI category and first alcohol use, current weekly alcohol use, and current weekly heavy episodic drinking in 3,514 (14.06% black) young adult female twins. Analyses were conducted separately in black and white women. Results: After adjusting for relevant covariates, in white women obesity was protective against alcohol use (hazard ratio = 0.83; 95% confidence interval [CI]: 0.73-0.93) and against weekly drinking (odds ratio [OR] = 0.36; 95% CI: 0.24-0.53) and weekly heavy episodic drinking (OR = 0.51; 95% CI: 0.31-0.82) among ever drinkers compared with women of ideal weight. Overweight women living with their parents were less likely to be weekly drinkers (OR = 0.31; 95% CI: 0.16-0.61), whereas overweight women who were not living with their parents were less likely to be weekly heavy episodic drinkers (OR = 0.51; 95% CI: 0.31-0.82). Among black women, obesity was not associated with any of the drinking outcomes; however, black women who were overweight and who reported that the majority of their friends were not weekly drinkers had greater odds of reporting weekly drinking than those of ideal weight (OR = 2.91; 95% CI: 1.33-6.39). Conclusions: Obese white women were less likely to ever use alcohol, be weekly drinkers, or be weekly heavy episodic drinkers than their ideal-weight peers. Body weight may affect drinking behavior in young women, and this effect may differ by race. Future research is needed to identify mediators and moderators of this relationship as well as to explore racial differences in the effect of body weight on drinking behavior.