Purpose: The authors evaluated the installation and use of sound-field systems to investigate the impact of these systems on teaching and learning in elementary school classrooms. Methods: The evaluation included acoustic surveys of classrooms, questionnaire surveys of students and teachers, and experimental testing of students with and without the use of sound-field systems. In this article, the authors report students' perceptions of classroom environments and objective data evaluating change in performance on cognitive and academic assessments with amplification over a 6-month period. Results: Teachers were positive about the use of sound-field systems in improving children's listening and attention to verbal instructions. Over time, students in amplified classrooms did not differ from those in nonamplified classrooms in their reports of listening conditions, nor did their performance differ in measures of numeracy, reading, or spelling. Use of sound-field systems in the classrooms resulted in significantly larger gains in performance in the number of correct items on the nonverbal measure of speed of processing and the measure of listening comprehension. Analysis controlling for classroom acoustics indicated that students' listening comprehension scores improved significantly in amplified classrooms with poorer acoustics but not in amplified classrooms with better acoustics. Conclusions: Both teacher ratings and student performance on standardized tests indicated that sound-field systems improved performance on children's understanding of spoken language. However, academic attainments showed no benefits from the use of sound-field systems. Classroom acoustics were a significant factor influencing the efficacy of sound-field systems; children in classes with poorer acoustics benefited in listening comprehension, whereas there was no additional benefit for children in classrooms with better acoustics.