A study begun in a Texas school district in 1988 focused on families of Mexican origin, studying characteristics of their schools and studying what the families and schools did or did not do to promote graduation from high school. The sample of 100 15-year-olds labeled as "at risk" was fairly typical of Latino students in the school district, with only about 13% receiving limited English proficiency services. Even parents with little or no formal education valued a high school diploma and understood its importance. The study found that school practices, rather than parent influence, were the primary cause of dropping out. Three practices in particular contributed to dropping out. The first was retention in grade, which resulted in over-age students with a sense of inadequacy. The second detrimental practice was tracking, or grouping students by standardized scores, which lessened student expectations and damaged self esteem. The third educational practice cited was the addition of passing an exit-level test as a requirement for obtaining a high school diploma. Especially in the lower academic tracks, preparation for these tests is inadequate, and students often drop out because of repeated failure. Students and parents certainly bear a share of the responsibility for continuing in school, but school practices are the main reason Mexican American students in this district dropped out. (Contains 3 figures, 2 tables, and 23 references.) (SLD)