In the context of college admissions, the current study examined whether differential prediction of first-year grade point average (FYGPA) by gender could be explained by an omitted variable problem--namely, academic discipline, or the amount of effort a student puts into schoolwork and the degree to which a student sees him/herself as hardworking and conscientious. Based on nearly 10,000 college students, the current study found that differences in intercepts by gender were reduced by 45% with the inclusion of academic discipline in a model that already included high school grade point average (HSGPA) and ACT Composite score. Moreover, academic discipline resulted in an additional 4% of variance accounted for in FYGPA. Gender differences in slopes were not statistically significant (p > 0.001) regardless if academic discipline was included in the model. The findings highlight the utility of taking a more holistic approach when making college admission decisions. Namely, the inclusion of noncognitive measures has benefits that are twofold: increased predictive validity and reduced differential prediction.