This study shows the relationship between English language proficiency and achievement. A consistent pattern is demonstrated that the English proficiency level of English as a second language (ESL) students can predict student performance on state measures --the high stakes Texas Educational Assessment of Academic Skills (TAAS). TAAS is a comprehensive assessment of the state-mandated curriculum in all subjects. Data indicates that students who have yet to reach a certain level of English language proficiency will not perform well on assessment measures of English, regardless of the subject being tested. It is argued that until ESL students have established a certain level of English language proficiency, it remains inappropriate for achievement tests in English to be used for student and school district performance accountability. This study also demonstrates that an underlying concern for the state of Texas should be that many ESL limited-English-proficient (LEP) students are taking more than 4 years to reach a minimum level of English. Efforts by the state should instead be focused on facilitating an appropriate timeline for LEP students to reach minimum levels of proficiency. Data-rich tables and figures appear throughout the text and appendices contain official state policy documents. Appended are the state test definitions and LEP Testing Policy, the history of State LEP Exemption Policy, and the Local District Language Proficiency Test. (KFT)