This article describes the development and construction of the Public Affairs Scale, specifically designed to assess student development in the three areas of the public affairs mission at Missouri State University. This development process involved shared governance, literature review, and other tools used to assess components related to public affairs. The article also explains the public affairs mission at Missouri State University, including definitions of themes and goals and select markers of that mission’s manifestation during the past 15 years. It provides a brief review of assessments used in universities to measure similar constructs, such as engagement and the public good. The Public Affairs Scale is shown to have feasibility (40 items), adequate to strong internal consistency, and construct validity. It appears sufficiently sensitive to capture differences between students and within students over time. The Public Affairs Scale has been used to assess the impact of a first-year service-learning initiative. Readers are encouraged to use it for further program evaluation and research.