New sport policies often prompt organizations in the field to alter their structures and processes. Little is known, however, about the tactics of those leading institutional change around sport policy. To address this gap, the authors draw on the concept of institutional entrepreneurship—the activities of actors who leverage resources to create institutional change. Using a qualitative case study approach, the authors examine how two coalitions that served as institutional entrepreneurs in Washington and Oregon created and passed the first youth sport concussion legislation in the United States. The analysis of this study reveals that these coalitions (including victims’ families, sport organizations, advocacy groups, and concussion specialists) engaged in political, technical, and cultural activities through the use of specific tactics that allowed them to harness expertise and resources and generate support for the legislation. Furthermore, the findings of this study suggest a sequencing to these activities, captured in a model of institutional entrepreneurship around sport policy.