This study examined high-stakes test performance of Limited English Proficient (LEP) students under the No Child Left Behind (NCLB) Act of 2001 in Ohio. NCLB identified problems of academic achievement gaps between LEP students and non-LEP students, yet there has been a significant lack of studies concerning the accurate academic assessment of LEP students (August and Hakuta, 1997, Coltrane, 2002). Four research hypotheses were examined with the fourth grade and the sixth grade Ohio Educational Management Information System (EMIS) data in the state reading, writing, and mathematics tests: (1) demographic diversity of LEP students, (2) significant levels of mean differences on high-stakes test performance between LEP students and non-LEP students, (3) interactive or causal relationships among student variables, school variables, and academic achievement, and (4) mixed effects of student and school variables, and their affect on academic achievement. Previous studies from the four most LEP populated states, California, Texas, New York, and Florida offered predictor variables in two levels for this study: the student level and the school level. The student-level variables included longevity, native language, gender, race, SES, migrant status, and English language proficiency, and the school-level variables were campus mobility and campus poverty. Analyses included multilevel, multivariate techniques, the Structural Equation Model (SEM) and the Hierarchical Linear Model (HLM). Among the findings were: (1) LEP students were diverse in race, gender, English proficiency, SES, native language, longevity, and academic achievement in Ohio, (2) there were significant differences in academic performance between LEP students and non-LEP students: LEP students showed lower performance, (3) student background variables did not explain a large portion of academic achievement, (4) more school-level variables need to be investigated, (5) campus poverty had the most influence on academic achievement of individual students, and (6) Hispanic race did not show negative effects on academic achievement, rather, positive effects on the fourth grade writing in high poverty schools. Suggested implications include: (1) schools can maintain high academic achievement with LEP students, (2) class desegregation may improve school achievement, and (3) review of term definitions, monitoring and implementing NCLB policies and funding are recommended.