In designing a curriculum to assist children in learning English as a second language (ESL), a thorough understanding of the differences between the first and second languages is essential. With such an understanding, problems and concepts that may cause language interference and learning difficulties can be identified and an appropriate curriculum that will best meet the needs of bilingual children can be designed. The recent low achievement of the children of the Mississippi Band of Choctaw Indians is due in part to lack of English language skills for academic or personal communication. An ESL curriculum has been developed to enhance the children's English language competence while encouraging retention of the Choctaw language and Choctaw cultural traditions. A formal evaluation was performed through the administration of the Language Assessment Scales (LAS) to 50 kindergarten through third-grade students twice a year over a three-year period. Through item analysis of the results, together with analysis of the children's speech and writing, phonological, morphological, syntactic, and semantic features in the two languages that were suspected of causing interference in English acquisition were identified and targeted in the curriculum, which is designed for three levels of English proficiency: non-English speakers, limited English speakers, and fluent English speakers. An intensive study of the Choctaw language and how it differs from English allowed the incorporation of instructional concepts aimed at enhancing the children's language skills affected by the absence or difference of particular structures in each language, and the concepts were selected based on the functional and meaningful applications of English in the children's environment. Appendices contain item analyses of LAS scores, a graph showing LAS totals for all schools for fall, 1983, by levels of proficiency, and a fold-out chart showing the ESL curriculum design for Choctaw children grouped by proficiency levels for the first through the fourth nine-week term. (MSE)