Untracking places previously low-achieving students (primarily from low-income and ethnic or language-minority backgrounds) in the same college preparatory academic program as high-achieving students. The Achievement via Individual Determination (AVID) program of the San Diego (California) schools shifts education policy for underachieving students to a rigorous curriculum with increased support for low-achieving students. The San Diego program has been extremely successful in preparing students for college. Forty-eight percent of the 248 students who completed 3 years of AVID enrolled in four-year colleges, 40 percent enrolled in two-year colleges, and the remaining 12 percent are working, traveling, or doing voluntary work. Parental income and education are not responsible for the impressive college enrollment figures, since students from the lowest income strata are enrolling in equal or higher proportion to those from higher income groups. The search for reasons for AVID's success indicates that teachers explicitly teach aspects of the implicit culture of the classroom and hidden curriculum of the school, and they mediate relationships among families, high schools, and colleges. AVID gives its students social and cultural capital. (Contains 43 references and 6 figures.) (Author/SLD)