Cross-national research finds that "shadow education" -educational activities outside of formal schooling -tends to confer advantages on already privileged students. Shadow education in the United States, such as test prep for college entrance exams, has received considerably less attention. Drawing on the National Education Longitudinal Study, we analyze the likelihood of participation in, and the implications of, SAT preparation. Social class inequalities in test preparation, particularly costly SAT courses and private tutoring, are notable and have at least moderate consequences for SAT scores and selective college enrollment. We also find racial/ethnic variations in the use of test preparation. We consider the implications of these findings for understanding shadow education, stratification and educational mobility in the United States.The SAT is arguably the single most important test for American high school students. Every year, more than 2 million young people take this standardized multiple-choice test and most four-year colleges and universities use the results to evaluate applicants from more than 20,000 disparate U.S. high schools (College Board 2007;Grodsky, Warren and Felts 2008). 1 In light of the growing importance of test scores for college admission over the past several decades (see Alon and Tienda 2007), it should not be surprising that SAT preparation services have developed into a lucrative multi-million dollar industry. The Princeton Review, one of the largest companies in this market, earned $110.4 million in revenue for its test preparation services in 2009 (Princeton Review 2010a). Such preparation includes expensive private courses and coaching as well as more moderately priced test prep manuals and computer software programs.A vociferous debate has emerged regarding the "fairness" of the SAT and the extent to which it should be used in the college admission process (Thernstrom and Glazer 1999; Lemann 1999). Indeed, over-reliance on SAT scores in college admissions has broad and clear-cut implications for issues of merit and diversity in the educational sorting and credentialing process (Alon and Tienda 2007). No less profound, especially for the question of merit, is the likelihood that access to and use of test preparation vary by the family background of students (Briggs Downloaded from 436 • Social Forces 89 (2) 2001; Powers and Rock 1998). Are children from well-resourced families more likely to participate in test preparation than poorer children? Does test preparation pay off in terms of higher examination scores and likelihood of admission to college, especially selective colleges? These questions resonate with prior work on educational stratification and its roots in family inequalities, but they also speak to the relevance of "shadow education" in the United States.Shadow education -a theoretical construct most often used in comparative education research -refers to educational activities, such as tutoring and extra classes, occurring outside of the formal channels of an educ...