This book explores the relationship between Spanish language usage, English language proficiency, and the long-term educational outcomes of Mexican American youths. Language use patterns and language attitudes were examined among 38 high school dropouts, 188 high school students, and 36 college students, all Mexican Americans in Chicago. Chapters review relevant research and literature, provide the problem statement and methodology, present comparative analyses of the data from each informant group, discuss relevant findings, and suggest areas for future research. Findings reveal that a high use of Spanish and favorable attitudes toward Spanish in no way hindered either English language proficiency or long-term academic achievement among Hispanic youth. Instead, these factors accompanied higher levels of achievement among the youth surveyed. Additionally, high levels of English language proficiency and positive attitudes toward English did not guarantee high levels of academic achievement. Several factors considered to be dropout indicators were found to be prevalent among all informants, which brings into question the true explanatory power of such characteristics. Finally, the informants in this study exhibited a distinct sociolinguistic profile compared to Mexican American populations elsewhere in the country. Policymakers and school officials need to identify and focus on the characteristics that affect academic achievement of their local population instead of concentrating on unfounded assumptions, superficial characteristics, and unreliable or inapplicable qualities from national studies. Appendices contain research questionnaires and related materials. (Contains 145 references, 24 data tables, and an index.) (TD)