This evaluation reviews efforts made by Illinois Action for Children (IAFC), with guidance from the Illinois Governor's Office for Early Childhood Development, to spur experimentation with new systemic change strategies to increase the number of children from priority populations--those considered to be the most vulnerable, with multiple risk factors--who are enrolled in high quality early learning programs. The Early Childhood Innovation Zones initiative, funded by a Race to the Top--Early Learning Challenge grant, supported capacity building efforts for organizations working with young children in 11 underserved communities, or Innovation Zones (IZs), across Illinois. The theory of action undergirding the IZ project calls for building capacity in these organizations to promote the implementation of system improvement strategies for increasing two primary outcome measures: (1) enrolling and serving more children (birth to kindergarten) from priority populations in early learning programs; and (2) increasing the number of early learning programs participating in ExceleRate Illinois, the state's quality rating and improvement system (QRIS). Illinois Action for Children's capacity-building efforts combined behavioral change theories with systemic thinking and community engagement strategies. These efforts were designed to help zones conceptualize concerns at the system level and to equip zone leaders with the skills and community partnerships needed to address these concerns. This study used a mixed methods approach to describe the strategies utilized by the IZs to improve enrollment and quality and evaluate the progress of capacity building efforts made by IAFC. The study is summarized in this report. [For the full report, "Illinois' Early Childhood Innovation Zones: A New Model for State Policy? IERC 2017-1," see ED574338. For the research highlights, "Illinois' Early Childhood Innovation Zones: A New Model for State Policy? IERC 2017-1. Research Highlights," see ED574339.]