Through several decades of research, a great deal has been written about trends in black-white test scores and the factors that may explain the gaps in different subject areas. Only a few studies have examined the changing relationships between gaps in students' test scores and family and school measures in nationally representative data over several periods. This article builds on this previous work and addresses some of its limitations by analyzing nationally representative data in 1972, 1982, 1992, and 2004 that provide consistent measures of high school seniors' mathematics achievement and several school and family measures. Together, these databases for four cohorts of high school seniors provide the opportunity to analyze associations between the gaps in black-white test scores and changes in family background and school characteristics (in terms of both changes in means and coefficients). The analyses reveal positive changes for black students relative to white students between 1972 and 2004, such as improvement in some socioeconomic family background characteristics. Yet, some school conditions (racial/ethnic and socioeconomic composition) did not improve for black students, and despite some beneficial changes, inequalities persist. (Contains 5 figures, 4 tables, and 7 notes.)