The Wallace Foundation's Principal Pipeline Initiative is an ambitious, multiyear effort supporting districts and partner institutions as they work to strengthen and align components of their work with new principals. Six large school districts that built principal pipelines as grantees saw notable, statistically significant benefits for student achievement across their communities. After three years, pipeline-district schools with newly placed principals outperformed comparison schools in other districts by more than 6 percentile points in reading and almost 3 percentile points in math, an unusual accomplishment.