This document outlines a developmental evaluation approach used by the Bill and Melinda Gates Foundation's Community Partnerships Portfolio to understand system change in the postsecondary field. It describes the current state of the postsecondary system and the goals and outcomes of the initiative. A developmental evaluation was used because the initiative was complex, innovative and untested. Key lessons included that developmental evaluation looks different than other types of evaluation by engaging partners, developing tools for multiple uses, and refining tools over time. The evaluation aimed to develop understanding of what the system change model might look like through a reflective process.