New findings from our five-year study on the impact of teacher stability on measurable student learning outcomes.
Between 2020 and 2025, we tracked 312 schools across four states to understand how teacher stability shapes student outcomes. The results are clear, consistent, and have direct implications for how districts invest in their workforce.
Headline Findings
- Schools with sub-10% annual teacher turnover outperformed peers by an average of 6.8 percentile points in reading growth.
- Each successive year a teacher remains in the same building adds measurable returns, with diminishing gains after year seven.
- Mentorship structures matter more than salary increases for first-year retention.
“Stability is a strategy. Treat it like one.”
Implications for Leaders
Retention is not an HR metric — it is an instructional strategy. Districts that protect teacher time, build collaborative cultures, and invest in instructional leadership see compounding returns over time.
DR
Dr. Rachel Muilenburg
Founding Director of Research