Abt Global conducted an independent review of the strength of evidence from the Principal Pipeline Initiative (PPI) evaluation. The Every Student Succeeds Act (ESSA)-informed review found that, overall, there were improved outcomes of the PPI at each of two time points that were statistically significant and there were no overriding negative effects in the following domains:

• Mathematics achievement (two and three years after the initial implementation of the PPI).
• Reading achievement (two and three years after the initial implementation of the PPI).
• Principal retention (two and three years after new principals are placed after the initial implementation of the PPI).

The achievement outcomes met ESSA Tier II evidence standards and the principal retention outcomes met Tier III evidence standards.