Limited-English-proficient (LEP) students who are not sufficiently proficient in English to participate effectively in an English-speaking instructional environment must be identified for placement in an appropriate educational program. Their progress through an instructional program that is designed to improve their acquisition of English language skills must also be measured both for purposes of exiting from the program and for program evaluation. Both placement and evaluation require a measure that assesses different levels of English-language proficiency. Attention is directed to the concept of language proficiency, how best to measure it with relevance to curriculum, appropriate levels of difficulty, and a meaningful frame of reference for the interpretation of scores for different populations. Attention is also directed to issues concerned with constructing an instrument that can serve both placement and evaluation purposes; that is, an instrument that can differentiate efficiently between English-proficient and LEP students yet, at the same time, provide efficient measurement of the progress of the lower-scoring LEP students. These issues are discussed with reference to the New York City Language Assessment Battery (LAB-1982). (Author)