Despite the visible popularity of policies "to end social promotion," little is known about the prevalence of grade retention in American schools or about the effects of race-ethnicity and other social and economic background characteristics on retention. We review the policy context of school retention and show that age-grade retardation has been common and growing in American schools from the 1970s through the 1990s. Our analysis focuses on the period from 1972 to 1998 and on grade retardation at ages 6, 9, 12, 15, and 17. By age 9, the odds of grade retardation among African-American and Hispanic youth are 50 percent larger than among White youth, but these differentials are almost entirely explained by social and economic deprivation among minority youth, along with unfavorable geographic location. Because rates of age-grade retardation have increased at the same time that social background conditions have become more favorable to rapid progress through school, the observed trend toward more age-grade retardation substantially understates growth in the practice of holding students back in school. While there is presently little evidence of direct race-ethnic discrimination in progress through the elementary and secondary grades, the recent movement toward high stakes testing for promotion could magnify race-ethnic differentials in retention.