In 2011, The Wallace Foundation launched a $75 million initiative to help six urban school districts develop a much-increased corps of effective school principals and to determine whether this improves student achievement, especially in the highest-needs schools.

Based on 10 years of research and work in the field, Wallace identified four key elements of a successful "principal pipeline" that produces a large number of high-quality principals: rigorous job requirements, high-quality training, selective hiring, and on-the-job evaluation and support.

During the course of the initiative, Wallace learned that principals often did not receive the help they needed to strengthen teaching and learning. "We began to suspect that gains in schools might not be sustainable without support from another position - the principal's supervisor in the central office," said Jody Spiro, the foundation's director of education leadership.

In response, Wallace launched the $30 million Principal Supervisor Initiative in 2014 to help school districts step up support for principals' supervisors, allowing them to focus more deliberately on helping principals improve instruction in schools. The five-year effort funds additional training and support for principal supervisors in 14 large urban school districts serving low-income children, including Tulsa, Okla., and Washington, D.C. Wallace is also supporting an independent evaluation of the initiative to help determine whether and how boosting the supervisor post leads to more effective principals.