The inquiry illuminated the way in which specific schooling practices enhanced or negated effects by analyzing data on pupils in different placement groups having Spanish as their first language, with little if any English language proficiency at the time of entering school. If pupils were placed inappropriately low, the end-of-program scores simply reflected prior rather than current learning. Participants were from 35 districts in 4 states (Texas, California, Florida, and Arizona) with substantial Spanish-speaking pupil populations. Collectively, the districts, schools, and classes represented the full diversity in instructional settings that typically serve Spanish-speaking children. All pupils received instruction in classes that entailed use of the English Language and Concepts Program for Spanish-Speaking Pupils, a product system designed for instruction with pupils for whom Spanish is their first language. Data sources were the Placement Aid Record used to select and assign pupils for instruction and the Unit Record sheet used to confirm learning and assign further instruction when needed. A functional relationship between the units completed and the effects obtained was found only for pupils placed at or above recommended levels. It was concluded that some schools chose to accelerate pupils, others to see regular progress, and others to simply maintain proficiencies pupils displayed upon entry. These choices reflected implicit teacher decisions rather than pupil capabilities. (NQA)