With increasing rates of autism spectrum disorders (ASD), public schools are straining to provide high-quality, evidence-based programs for these students. Most current evidence-based practices for students with ASD were designed for use in one-on-one or highly controlled settings. Little research to date has examined the effectiveness of specific techniques in the context of school systems. The purpose of this project is to conduct a randomized trial of an intervention called Classroom Pivotal Response Teaching (CPRT), an intervention specifically adapted for use in classrooms for children with ASD. The trial will study children in preschool through fifth-grade classrooms to determine whether the program improves students' communication, object play, academic and social skills, on-task behavior, and progress toward IEP goals, including an examination of moderators and mediators of outcomes. The study will also examine teacher fidelity of implementation, moderators and mediators of teacher fidelity, and sustainability of program components. A randomized design, with 108 classrooms randomized to 3 groups, will be used to study the efficacy of the CPRT intervention over 4 years. In the first year, there will be a treatment group (A) and control group (B), as well as a waitlist group (C) who will not participate in the first year. In the second year of the study, the former control group (B) will be the treatment group, and the former waitlist group (C) will be a new control group. By the end of year 3, all groups will have received treatment and entered the follow-up phase. Teachers will receive a coaching "booster" each year after their training year. Assessment data will be collected for groups A and B in the first year and for all three groups in the remaining years.