Do district policy changes that increase access to full-day school-based pre-kindergarten relate to improved 2nd grade academic outcomes? How? A study from Start Early, NORC at the University of Chicago, and the University of Chicago Consortium on School Research examined these questions based on a set of Chicago Public School (CPS) policy changes that began in 2013-14. The authors used advanced statistical techniques to examine the relationship of funding full-day pre-k classrooms in communities CPS had historically underserved and student achievement. Results show that CPS policy efforts may help close achievement gaps, and the authors conclude that promoting access to school-based full-day pre-k is an important district policy lever when considering how to achieve greater equity and access.