Data collected during the first year of a 3-year study are reported. The study evaluated the effectiveness of a variety of special services provided to approximately 10,000 language-minority limited-English-proficient first- and third-grade students in English-medium classrooms in a national sample of 18 school districts. Services studied are not limited to those funded under any one program or by any single source. The present report summarizes the characteristics of the study's students, services, and schools. The first chapter offers background information, and the second chapter gives an overview of the study's design and implementation. Chapters 3-9 discuss the following topics: home and parent characteristics (family background, home language use, parent interest in education, and relationships among these characteristics); student characteristics (demographic, oral language proficiency, and academic aptitude); the school context (student body characteristics, academic climate, school language environment, provision of relevant teacher training, principal involvement, attitudes of non-language-minority parents, and program exit and entry policies and practices); elements of instructional services (language of instruction, curriculum design, materials, and staff); service clusters and sequences; student academic performance; and "other outcomes." The final chapter summarizes the findings and discusses implications. A 66-item bibliography is included. Appendixes include a glossary, a description of test scores and variables, an explanation of methodology, and technical analyses of two tests. (MSE)