Few classroom measures of English language proficiency have been evaluated for reliability and validity. This research examined the concurrent and predictive validity of an oral language test, titled A Developmental English Language Proficiency Test (ADEPT), and the relationship to the California English Language Development Test (CELDT) in the receptive/listening and expressive/speaking domains. Four years of retroactive data representing 392 student records were obtained from a local urban school district in Los Angeles County with a significant proportion of English language learners. After preparing the data file for analysis, data was analyzed using the Statistical Package for the Social Sciences (SPSS) system. Cronbach's alpha was used to analyze the internal consistency of ADEPT. Pearson r analysis was performed to examine concurrent validity and predictive validity. Findings indicated moderate to high correlation coefficients of internal consistency in the first three levels of ADEPT. Concurrent validity results varied depending on the school year. In the most recent school year, 2012-2013, positive moderate to strong correlations were found. This relationship was weaker in each previous year. Overall, correlations increased and remained positive as sample size increased but predictive validity was weak for all three sets of comparative years. These findings support the use of ADEPT as a multiple measure, as a monitoring tool and to inform instruction. [The dissertation citations contained here are published with the permission of ProQuest LLC. Further reproduction is prohibited without permission. Copies of dissertations may be obtained by Telephone (800) 1-800-521-0600. Web page: http://www.proquest.com/en-US/products/dissertations/individuals.shtml.]