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This article was retrieved from the online version of the ASCD Educational Leadership April 2021 Issue. Articles in this month's issue focus onThe Empowered Principal. This article and other helpful resources can be found at the following link:

What Great Principals Really Do

Jason A. Grissom, Anna J. Egalite and Constance A. Lindsay

A new research study sheds light on the impact of effective principals—and what makes them different.

A school's success is largely determined by the effectiveness of its principal—decades of research have made this clear. Less settled is the question of what principals need to know and do to drive positive outcomes in their schools.

Thousands of studies have addressed some facet of this question, but making sense of their findings is a big challenge, and not just because of the volume. Studies vary widely in the specific component of principals' work they examine, their data collection approaches, their methods of analysis, and the quality of the research.

In a recent report funded by The Wallace Foundation, we wrangled the evidence on the connection between school principals and school outcomes, focusing on research conducted in U.S. schools since 2000 that connects principals to student achievement, absenteeism, teacher turnover, school climate, and other important markers of successful schools (Grissom, Egalite, & Lindsay, 2021). Several important themes emerged, including just how important principals are in driving school outcomes and the commonalities in what effective principals do—interacting with teachers around instruction, building strong climates where teachers collaborate, and managing strategically. We also delved into the importance of leading for equity. Let's look at these themes more closely.

The Principal Is Principle

Just how large of an impact does a strong principal have on student achievement? To quantify the answer to this question, we identified six studies conducted across four states and two large urban school districts that leveraged administrative data over long periods (Bartanen, 2020; Branch, Hanushek, & Rivkin, 2012; Chiang, Lipscomb & Gill, 2016; Dhuey & Smith, 2018; Grissom, Kalogrides, & Loeb, 2015; Laing et al., 2016). The longitudinal nature of the data was key because the researchers could observe the same schools being led by different principals and the same principal leading different schools in different years. With this mix, we were able to isolate student outcomes that can be attributed to the principal from the effects of other factors beyond the principal's control (like what neighborhood the school is in).

These studies showed that the quality of a school's principal is a big determinant of student achievement. To illustrate how big, consider a typical school that has a below-average principal—say, a principal at the 25th percentile of effectiveness (defined by student test score growth). In the analysis of our report, we show the gains that could be expected if the school district replaced this principal with an above-average one (that is, at the 75th percentile of effectiveness). Students in the school would gain about three months of learning in math and reading in subsequent school years.

An important addendum to this finding that principals are a big determinant of student achievement is that principals also affect all students in the school. And principals impact not just student learning but the experiences that students—and teachers—have in their schools. The principal can influence how often a student is absent or suspended, and how likely a teacher is to stay in the school for another year. For these reasons, it is hard for us to imagine a better investment in a school than the quality of its leadership.

What Drives Principal Success?

After quantifying the effect that principals can have on a school, we tried to discover what effective principals know and do. Although the research we reviewed took on many approaches and perspectives, we found three overlapping domains of skills that strong principals have mastered—(1) instruction, (2) people, and (3) the organization (see Figure 1).

Figure 1. Principal Skills and Behaviors to Improve School Outcomes

From Grissom, Egalite, and Lindsay. How Principals Affect Students and Schools, 2021.

Instruction refers to skills that directly support teachers' work in classrooms. Principals need to be able to differentiate effective and ineffective instructional approaches and make useful suggestions about what teachers might do differently. People skills are about building and maintaining relationships: good communication skills, caring, and the capacity to build trust within the school community. Skills related to the organization are those that would be necessary to run any complex entity, not just a school. These include data use, strategic thinking, and ability to allocate resources to advance school goals.

Effective principals draw on all three sets of skills to engage in the behaviors or practices that drive a successful school. Our review identified four sets of practices:

1. Instructionally Focused Interactions

The close work principals do with teachers to improve instructional practice has three dimensions. The first is leveraging teacher evaluation. High-quality evaluation systems center on structured, rubric-based teacher observations to improve teacher practice and student achievement. Principals are the linchpin of these systems, building buy-in, putting in the time to conduct observations, and taking care to ensure that ratings are accurate so that they can be acted on.

Second, and closely related, is feedback and coaching. Strong principals use what they observe in classrooms to give teachers useful feedback, which evidence suggests can raise teachers' impacts on their students. Third, effective principals use data to guide specific instructional decisions, drive the school's overall instructional program, inspire action around improvement, and monitor the school's progress toward its goals.

2. Building a Productive School Climate

A robust school climate is associated with many benefits. For example, teachers' instructional effectiveness improves more rapidly in schools with strong professional climates and student test score growth is higher in schools where the climate features an academic focus.

Principals can contribute to a positive school climate by helping teachers feel empowered and helping students feel safe, valued, and supported. Principals draw on their emotional and social intelligence to foster a school environment that promotes trust, collaboration, engagement with data, and continuous improvement. Efforts to build a productive school environment extend to parents and other community stakeholders, too. Effective school leaders may go to great lengths to support and affirm the local community's culture, language, and traditions.

3. Facilitating Collaboration

Collaboration around instruction and learning can drive student outcomes, but it doesn't happen by accident. Principals encourage it by ensuring common planning time for instructional teams and by setting up and maintaining high-functioning professional learning communities (PLCs). PLC success varies not only across, but also within schools, so principals must be intentional in their design and continuously engage with all PLCs in their school. They should explicitly connect them to other learning opportunities for teachers, like in-service trainings, and leverage the expertise of others in the school to push PLC work.

4. Strategic Management

The final area is strategic management of personnel and other resources. Strategic means that principals optimize how resources are used or allocated to support teaching and learning. Research documents several resources that successful principals manage strategically. An example is time, either their own or the school's.

The biggest resource a school has, however, is its people, and evidence is clear that strategic personnel management can push school improvement. For one, principals who consistently hire strong teachers see higher school growth. To consistently hire well, principals have to make hiring decisions based on evidence about what makes teachers effective. Strategic principals also recognize that some teachers may be more effective in some grades or with some groups of students, and they assign them accordingly. They also take care to disrupt patterns of assignment inequity—namely that low-achieving or low-income students often are assigned to less experienced or less effective teachers. Finally, good principals take steps to reduce overall teacher turnover in their buildings, especially among their best teachers.

Leading for Equity

Another factor that drives principal success is that effective leaders bring an equity lens to their work. Principals play an important role in the closing of achievement and opportunity gaps for historically marginalized groups. A growing body of mostly qualitative work demonstrates the channels through which principals' equity-oriented practices can serve these goals.

For example, in working with teachers on instruction, equity-focused principals focus on alternative instructional approaches (such as culturally responsive teaching) to meet the learning needs of all learners in the building. They engage teachers in specific professional development around serving the needs of marginalized populations.

They communicate high expectations for teaching and learning of marginalized students. In building a school climate, they ensure that diverse students are—and feel—valued. They attend to disparities in how students from different groups are treated, such as addressing racial gaps in student discipline practices. They encourage collaboration not only within the school, but also with external stakeholders explicitly around meeting the needs of marginalized students.

Finally, they infuse equity into organization management practices, including ensuring that students have equal access to the school's strongest teachers, regardless of their background or status.

Takeaways for School Leaders

Having an effective principal in a school really matters—more, we think, than researchers often have emphasized in the past. How well the principal does their job impacts outcomes for every student and teacher in the school, plus the community beyond. Staffing a building with an effective leader and empowering them to implement high-leverage practices is likely among the best investments a school district can make in a school.

Our review of the best-available evidence suggests that successful principals engage with teachers' instruction by harnessing observation, providing thoughtful feedback, and making use of achievement and other data. They take intentional steps to build a productive school climate where people trust one another and have good relationships. They encourage collaboration. They manage personnel and other resources strategically. And they implement each of these practices in ways that advance equity among students. Often principals are looking for ways to cut through the complexity of their work to bring focus to what they should do to make a positive difference for student achievement and other outcomes in their school. These areas are good places to start.

These areas can also become points of focus for districts' support of their principals. In recent years, many districts have reorganized principal supervision away from operations and compliance toward coaching and feedback, often with an emphasis on how principals engage with instruction (Goldring et al., 2020). Our synthesis suggests that this shift makes sense. It also points toward the need for supports for principals to build their capacity in other key areas—climate, fostering collaboration, strategic management—which districts can provide through work with supervisors or mentors, or through other in-service professional learning opportunities. Empowering principals by building their leadership capacity where it matters can be a worthwhile strategy for school improvement.


Bartanen, B. (2020). Principal quality and student attendance. Educational Researcher, 49(2), 101–113.

Branch, G. F., Hanushek, E. A., & Rivkin, S. G. (2012). Estimating the effect of leaders on public sector productivity: The case of school principals (No. w17803). National Bureau of Economic Research.

Chiang, H., Lipscomb, S., & Gill, B. (2016). Is school value added indicative of principal quality? Education Finance and Policy, 11(3), 283–309.

Dhuey, E., & Smith, J. (2018). How school principals influence student learning. Empirical Economics, 54(2), 851–882.

Goldring, E. B., Clark, M. A., Rubin, M., Rogers, L. K., Grissom, J. A., Gill, B., et al. (2020). Changing the principal supervisor role to better support principals: Evidence from the Principal Supervisor Initiative. Vanderbilt University and Mathematica.

Grissom, J. A., Egalite, A. J., & Lindsay, C. A. (2021). How principals affect students and schools: A systematic synthesis of two decades of research. New York: The Wallace Foundation.

Grissom, J. A., Kalogrides, D., & Loeb, S. (2015). Using student test scores to measure principal performance. Educational Evaluation and Policy Analysis, 37(1), 3–28.

Laing, D., Rivkin, S. G., Schiman, J. C., & Ward, J. (2016). Decentralized governance and the quality of school leadership (No. w22061). National Bureau of Economic Research.

Jason A. Grissom is the Patricia and Rodes Hart Professor of Public Policy and Education at Peabody College, Vanderbilt University, and faculty director of the Tennessee Education Research Alliance. Anna J. Egalite is an associate professor in the Department of Educational Leadership, Policy, and Human Development at North Carolina State University. Constance A. Lindsay is an assistant professor of education leadership in the School of Education at UNC Chapel Hill. Follow them on Twitter @JasonAGrissom@annaegalite, and @Dr_ConstanceL.