This research tests the strength and generalizability of Gottfredson and Hirschi’s theory by comparing the ability of self-control to predict substance use for heterosexual and non-heterosexual groups. Self-reported data from college students were gathered and key variables included sexual orientation, self-control (as measured by the Grasmick scale), alcohol use, marijuana use, and drug use. Linear and logistic regression models were used for the analysis. Results from the multivariate models found that self-control was a stronger predictor for the heterosexual sample. Self-control was a statistically significant predictor for two models for the heterosexual sample (alcohol consumption and marijuana use), while it was never statistically significant for the non-heterosexual sample. Despite having similar levels, self-control was a stronger predictor for substance use for heterosexuals. Heterosexuals and non-heterosexuals have different experiences as a result of their sexual orientation, which lead to varying relationships between self-control and substance use.