Principals are the second-largest school-based contributor to K-12 students' academic progress. However, there is little research evaluating whether efforts to develop principals' skills improve school effectiveness. We conducted randomized controlled trial studies of the impacts of a professional development program called the Executive…

A multi-cohort cluster randomized trial was conducted to estimate effects of rich vocabulary classroom instruction on vocabulary and reading comprehension. A total of 1,232 fourth- and fifth-grade students from 61 classrooms in 24 schools completed the study. Students received instruction in 140 Tier Two vocabulary words featured in two…