Prevalent definitions of the achievement gap conceptualize it as the difference in achievement between white and minority students. Recent research, however, points to numerous gaps both within and between groups. This study explores a further conceptualization of achievement gaps by looking at the "underachievement gap"--the difference between students from capital-rich backgrounds who choose to attend postsecondary institutions and those who do not. Using the NELS:88 database to examine differences in college enrollment for Hispanic, black, and white students separately, results indicate being held back, number of hours worked during the week, and how far the student expected to go in college were significant predictors for all three groups. With all students combined into one sample, HGLM analysis revealed race/ethnicity generally proved not to be a significant predictor of postsecondary enrollment. (Contains 6 tables.)