Good leadership can be a stabilizing force. Effective principals increase student achievement, reduce absenteeism, and significantly improve teacher retention, researchers from George Mason University conclude in a 2021 study. But to keep both students and teachers coming back—and flourishing—you need to train principals early.

Researchers analyzed data from nearly 5,000 newly hired principals who completed mandatory training courses that developed their ability to “set high-performance expectations,” connect a shared vision for the school with the “instructional mission,” and establish data-driven programs to “facilitate and inform these instructionally-focused interactions,” among other skills.

Schools get the greatest benefits when the principals’ training takes place within the first 2 years of leadership: Under those circumstances, the study found continued improvements to student achievement and teacher effectiveness, along with an 18% reduction in teacher turnover.