This study analyzes college graduates in the workplace to evaluate the effects of horizontal mismatches between education and jobs on wages and mobility. Using the Heckman-Lee and probit models, this study shows that a gender wage gap still exists. However, the size of the gender wage differential depends on the extent of mismatch. Specifically, the female wage penalty decreases from closely-related to somewhat-related and then increases from somewhat-related to not-related. We also show that the wage penalty motivates females to change jobs more often.