Helping principals improve their leadership practices is a common use of federal funds and one way to improve instruction and student achievement. The study highlighted in this one page report sought to better understand the effectiveness of an intensive principal professional development program focused primarily on helping principals conduct structured observations of teachers' classroom instruction and provide targeted feedback based on those observations. One hundred elementary schools participated in the study, with half randomly assigned to receive the program. The study compared student achievement and teachers' perceptions of principals' practices in schools that received the professional development program with those that did not. The results provide evidence about the program's effectiveness and which principal practices are associated with student achievement. [For the full study, "The Effects of a Principal Professional Development Program Focused on Instructional Leadership. NCEE 2020-0002," see ED599489. For the appendices to the study, "The Effects of a Principal Professional Development Program Focused on Instructional Leadership: Appendices. NCEE 2020-0002," see ED599491.]