This study compared college course grade outcomes, both during and after high school, of dual-enrollment students to those of traditional students. The study was based on a large, multiyear sample of Iowa high school and community college students. The results showed that while in high school, dual-enrollment students consistently outperformed traditional students in community college courses. However, much of the difference might be due to underlying differences in the two groups associated with the type of college the students chose to attend after high school (i.e., four-year vs. two-year). Dual enrollment students tended to perform about the same as traditional students in terms of post-high-school community college course grades. For students who enrolled in four-year institutions after high school, analyses of college course grade data suggested a small positive effect of dual enrollment on first-year college grade point average (GPA).