Despite being largely preventable, unintentional injuries are the leading cause of pediatric mortality in the state of South Carolina, USA. Deliberate policy is needed to encourage transformative change in preventing childhood injuries. However, injury prevention advocates across the state have yet to formalize a collective message to effectively engage policymakers regarding injury prevention issues. To address this concern, this study surveyed Safe Kids South Carolina child injury prevention advocates as well as state legislators and legislative staff with the goal of assessing and growing current knowledge of injury prevention and capacity to engage in legislative advocacy. One hundred seventy-four advocates and fifteen state legislators and legislative staff completed a survey of knowledge of injury prevention, perceptions on the importance of various injury prevention issues, organizational capacity to engage in advocacy activities, the impact of advocacy efforts, and legislative action taken as a result of injury prevention advocacy. In addition to the survey, structured interviews of legislators and staff were also conducted, and findings were compiled to inform advocacy and capacity-building activities for Safe Kids coalition members. Activities included a training session on effective advocacy techniques, child passenger safety laws, and legislative talking points for advocates to use during a structured advocacy event at the South Carolina statehouse. From those activities, Safe Kids coalition members received pledges from policymakers to introduce or co-sponsor child passenger safety guidelines.