By Contributor,Linda Darling-Hammond

Copyright forbes

A teacher instructs students during a lesson.

Each fall, as school bells ring again, we also hear a chorus of voices from the schoolhouse to the statehouse bemoaning the growing challenge of teacher shortages. The most recent state data show more than 400,000 teaching positions either unfilled or filled by teachers not fully certified for their assignments. The comparable number was about 300,000 in 2023 and is nearly double the 200,000 vacancies verified in 2022 as unfilled by qualified teachers.

While these reports generally give rise to hand-wringing about the problems of teacher recruitment, the shortage of qualified teachers is almost entirely due to failures of teacher retention. Nine of 10 vacancies each year are due to teachers leaving since the year before—and only 16% of those who leave identify retirement as their primary reason.

Understanding America’s Teacher Exodus

Why do teachers leave? There are numerous reasons, including unsupportive school leadership, burnout, and chronic stress (often exacerbated by untenable workloads, as U.S. teachers have heavier teaching loads than teachers in other countries). Teachers who are underprepared and unmentored leave at double the rate of well-prepared and supported teachers. Low salaries are a key problem, especially in cities where costs of housing have made it impossible to live within a reasonable commute to school.

Importantly, as Chad Aldeman details in a recent article, while school funding has increased over the years, teacher pay has remained largely stagnant. When teachers enter the profession, they take on a steep “pay penalty,” earning approximately 25% less than college graduates in other professions. The competitiveness of teachers’ wages has declined significantly since the 1990s, when teachers’ salaries nearly reached those of other college graduates. At that time, teacher attrition rates were also nearly 40% lower than they are now.

The High Costs of Teacher Turnover

The financial cost of teacher turnover is significant for districts. Every departure costs districts an estimated $12,000 to $25,000, depending on district size. That figure includes separation costs, plus the expense of recruiting, hiring, and onboarding replacements. When turnover is high, those costs compound year after year, eating into budgets that could otherwise fund instructional materials, student supports, mentoring, or competitive salaries.

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The human cost of teacher attrition is steep as well—and it’s borne most heavily by the students who can least afford it, as turnover is typically greater in schools serving the least advantaged students. Research shows that high rates of teacher turnover reduce student achievement. Furthermore, when schools can’t hire enough fully prepared teachers, they often turn to underqualified staff, increase class sizes, or cancel courses altogether, further undermining student learning. Sometimes, students cycle through multiple short-term substitutes in a single semester, learning little along the way.

Equally costly is the disruption turnover causes, which makes steady progress difficult for schools. Replacing a single teacher costs thousands of dollars, but when multiplied districtwide, the cost can escalate into the millions. Frequent churn destabilizes school communities, disrupts student learning, and diverts time and funds from strengthening instruction. In short, turnover is not only expensive, it also erodes the foundation needed for school stability and continuous improvement.

District leaders always face difficult decisions about where to allocate resources, but they would be wise to prioritize investments in teacher retention if they want to support learning recovery and promote student success.

Establishing a Stronger, More Stable Teacher Workforce

There are several things policymakers can do to create a stronger, more stable teacher workforce.

Create high-retention pathways into the profession: One important step to stem shortages is to create high-quality, affordable pathways to recruit and hire fully prepared teachers, who are more effective and who stay longer in the profession. A new strategy, taken up by districts and states across the country, is to develop teacher residencies, which productively address teacher shortages while improving teacher preparation. Residencies are created through partnerships between districts and teacher preparation programs that jointly recruit and train teachers in high-need fields. By providing robust financial and educational support, residencies attract diverse candidates who are coached by the best teachers in the district while taking highly relevant credential coursework. In return, teacher residents pledge to work for several years in the district. Research shows that residency graduates are more effective and stay in teaching at much higher rates than other hires. Participation in these and other quality preparation programs requires federal and state financial aid to enable teachers to become prepared while reducing the crushing loan burdens most experience.

Improve school conditions: In addition to wise recruitment, districts need to improve teaching and learning conditions to support retention in ways that not only reduce shortages but also support greater teaching ability. A new review conducted by the Learning Policy Institute and published by the Thomas B. Fordham Institute shows that teachers don’t stop improving after their early years; gains in effectiveness continue as teachers gain experience, especially when they are supported by strong colleagues, effective administrators, and stable teaching assignments. This matters now more than ever: as schools work to accelerate post-pandemic learning recovery, particularly for the most vulnerable students, they need the deep instructional expertise that experienced educators can provide.

Develop effective school leaders: Particularly important for retaining teachers is preparing principals who can create a shared mission, a positive school climate, a collegial environment in which teachers have time and opportunity to work and plan together, and teacher engagement in decision-making—all things that matter greatly to teachers when they are deciding whether to stay in the profession.

The truth is simple: allowing the teaching profession to erode is penny wise and pound foolish. When we invest in teachers—through competitive pay, strong preparation, and effective retention strategies—we not only honor their work and break the chronic teacher shortage cycle, we save districts money, stabilize schools, and improve outcomes for students.

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