This document evaluates the effectiveness of the Los Angeles Unified School District's Academic English Mastery Program, a program designed to serve students whose lack of proficiency in standard American English is an impediment to academic performance. This study used random sampling, experimental and control groups, and three principle data collection instruments (writing and speaking language assessment measures, teacher surveys, and observation checklists). Three main conclusions are drawn: (1) The Academic English Mastery program is an effective program for improving academic use of the English language for African American speakers of non-mainstream English; better utilization of the program improved student progress, and program effectiveness can be improved if teachers are motivated to implement and utilize program principles to their fullest extent; and teachers with more experience and education are more successful in improving student achievement. Given these results, recommendations are made for expanding the program, including focusing on other nonstandard English language minorities in future program evaluations and conducting longitudinal studies to examine the long-term impact of the program. Included are an executive summary, several tables, an explanation of purposes and methods, a summary of findings, conclusions and recommendations, two appendices (the teacher survey and the observation matrix), and extensive references. (KFT)