Educational opportunity in the United States and Mexico is an important factor in the process of expanding social and economic opportunities, as well as political and civil rights in both countries. Yet, by national and international indicators, many Mexican American and Mexican children are underserved by public schools in both countries; and very little research in education addresses the issue from a binational perspective. This paper addresses the need for further binational research by presenting a qualitative study exploring the structure of Mexican primary schooling and thereby raising questions for further study. More specifically, the "el turno escolar" (the school shift) and the "el grupo escolar" (the school group) are explored through a secondary data analysis of interviews and observations gathered in 2004.