There is no more difficult job in education than turning around a broken school that struggles with poor academic performance, low staff morale and chronic problems with discipline and attendance.

But that is what many principals are asked to do, often without the training and support they need to be successful.

Recognizing that principals play a key role in driving student achievement, school districts are now paying more attention to how they groom and support school leaders.

Urban school systems across the country, including those in the District and Prince George’s County, Md., are creating principal pipelines meant to grow talent from within. The goal is to identify talented teachers and assistant principals and train them to become leaders who can transform schools.

“We have this large pool of assistant principals to pull from, but what we were finding in some instances was they didn’t have all the skills they needed to be successful at the principal level,” said Doug Anthony, who leads the office of talent development for Prince George’s County Public Schools. “We recognized that we needed to build a really strong bench of qualified applicants.”

Anthony has helped overhaul Prince George’s County’s approach to cultivating, hiring, training and supporting school leaders during the past four years, aided by a $12.5 million grant from the Wallace Foundation.

The school system now runs a program to help orient first- and second-year assistant principals, and two dozen of the most promising assistant principals go through a year-long training program for aspiring principals. Prince George’s also has partnered with several local universities to ensure that principal candidates emerge with the skills that the school system seeks.

When a vacancy arises, applicants go through exercises meant to simulate the demands of the job: They watch a teacher on video and then explain how they would coach that teacher to improve, and they are handed a problem and asked to solve it.

“We want to see: Did you try to solve the problem yourself, or did you engage other people and resources to facilitate a resolution?” Anthony said. “The job of a principal is too important and too complex to have one person try to manage it all.”

Anthony said that Jean-Paul Cadet, principal of Oxon Hill High School, is a leader who has figured out how to make his school stronger by delegating responsibilities to teachers. Cadet received The Washington Post’s 2015 Distinguished Educational Leadership Award for his work at the Prince George’s school.

“I really want to be able to almost use him as a lab school to bring aspiring leaders in to see what he does,” Anthony said.

The Wallace Foundation has dedicated tens of millions of dollars to helping Prince George’s and five other school systems build principal pipelines that incorporate all the features that research says are important for success.

The foundation decided to invest in building talent pipelines in 2010.

It’s still too early to gauge whether student achievement is improving as a result. But Jody Spiro, the foundation’s director of education leadership, said superintendents in the six participating districts already rave about how much stronger principal applicants are now compared with several years ago.

“We’re delighted to hear that,” she said. “It’s hard to overestimate the important effect of a terrific principal.”

The District’s public school system has received a separate Wallace Foundation grant to strengthen the skills of managers who supervise and coach principals. The city has been one of the nation’s leaders in developing an internal principal pipeline, Spiro said.

“We have really amazing people in DCPS,” said Jason Kamras, chief of human capital for D.C. Public Schools. “We wanted to make sure that we were doing everything we could to develop them and support them and invest in them to become the next generation of school leaders.”

Rapid principal turnover has made it difficult for reforms to take root in some city schools, including in those with the lowest-performing students. So the school system recently created the Mary Jane Patterson Fellowship, named after the first African American woman to earn a bachelor’s degree, who was a principal at the city’s Dunbar High School.

The fellowship is an intensive 18-month program meant to turn talented teachers and assistant principals into successful principals. Of the first cohort of fellows, who finished last year, eight became principals and two became assistant principals.

One was Eric Bethel, an award-winning elementary school math teacher who is now in his first year at Turner Elementary in Southeast Washington, a long-struggling school where most students live in poverty and only about one in five is proficient in reading.

Bethel said that his training gave him more tools with which to confront challenges, and also the support of a group of like-minded colleagues who are going through many of the same struggles.

Every day, he and other first-time principals share questions, answers and advice on e-mail. “That’s been tremendously valuable,” Bethel said.

Still, training couldn’t prepare Bethel for everything.

“I had no idea — the volume and the intensity of the work. ... The e-mails are a hundred-plus per day, the parents that want to speak to you, the staff that need you, the student concerns, the central office. The pace is relentless,” he said. “I’m exhausted.”

Kamras said he’s confident that Bethel will succeed because Bethel has proved himself during his years with the school district.

“We work really hard to find the right people to come be principals at DCPS. The truth of the matter is, you’re never totally certain about someone until they’re here,” Kamras said. “That’s what’s great about a program like Patterson. I know Eric Bethel personally. I believe in him 110 percent.”

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