Research has focused on four groups of factors and the achievement gap: (1) student characteristics (high school GPA, attendance patterns, courses taken in high school, participation in extra-curricular activities, etc.); (2) family characteristics (family structure, in home, parents' level of education, mobility, etc.); (3) school-based characteristics (instructional strategies, class size, expectations, curriculum, staff-collegiality, etc.); and (4) socio-cultural factors (cultural attitudes, racism, differential social "privileges," etc.). The factors with the consistently largest impact on SAT and ACT scores are student academic characteristics: their grade point average, their coursework, their academic preparation. While you can't discount the impact of the other factors it is clear that school-level factors account for the greatest portion of the achievement gap. To reduce the SAT/ACT achievement gaps it is important to have students take rigorous high school classes and assure their success in those classes. (Contains 8 online resources.)