Recognizing the essential value of the arts, the Illinois State Board of Education (ISBE) included the arts as an indicator of school quality and student success in the state's Every Student Succeeds Act (ESSA) plan, which the U.S. Department of Education approved in August 2017. The indicator currently has no weight in Illinois's accountability and support system, but in 2017, the Illinois board committed to weighting the indicator after a sound method of measurement is determined. The Illinois Arts Indicator Work Group formed in January 2018, and the board asked it to recommend both the measure and weight. Chaired by Arts Alliance Illinois and the Chicago-based nonprofit Ingenuity, the work group formed a data and research team, which conducted the most extensive analysis to date of Illinois statewide arts education data. After more than a year of deliberations, the work group recommended a composite measure that combines student participation in arts coursework, quality of instruction, and student voice and provides a comprehensive, nuanced picture of the arts in Illinois schools. It recommended using these same submeasures for elementary and high schools. This article describes how the Illinois Arts Indicator Work Group and its process shed light on how arts educators and state boards across the country can collaborate to create innovative policy. Additionally, it discusses guiding principles established by the work group and how the group incorporated student input. It concludes with ways state boards can engage the arts education community.