The primary responsibility for engaging children in opportunities to be physically active and learn physical skills rests with school physical education. This study evaluated the effects of a combined health-related curriculum and inservice program on the quantity and quality of elementary school physical education lessons. Seven schools (N = 28 fourth-grade classes) in one district were randomly assigned to one of three conditions: 10 classes were taught in their usual manner by classroom teachers (Control [CO]); 10 classes were taught by trained classroom teachers (TT) who received inservice training and follow-up consultations; and 8 classes were taught by physical education specialists (PES) hired by the research project. Student activity level, curriculum context, and teacher behavior were directly observed and coded during a sample of 112 lessons over an 8-month period. Results indicated significant differences in both the frequency and mean length of classes (PES, 26.7 min; TT, 23.4 min; CO, 18.9 min). Additionally, the curriculum and inservice program equipped trained classroom teachers to provide significantly better classes than were provided by controls in terms of student activity engagement, lesson context, and active instructional behavior, though their classes did not match the quality of those taught by the physical education specialists. This study is unique in its use of direct observation of lessons to assess a curriculum and inservice intervention.