This article presents a case study of the political controversy in 1995 and 1996 between the United States Centers for Disease Control and Prevention (CDC) and the National Rifle Association (NRA) over whether the CDC should conduct policy research on firearm-related violence as a public health issue. In 1996, largely as a result of the NRA's lobbying efforts, Congress curtailed the CDC's authority in addressing firearm violence as a public health problem by redirecting funding toward research on traumatic brain injuries. In essence, the CDC was relegated to the domain of compiling and reporting statistical nationwide data on firearm injuries and deaths. For its part, the NRA demonstrated its power and effectiveness as a single-issue interest group in mobilizing its resources to battle the CDC in the public arena. This study focuses on the strategies and tactics that the NRA used and explores reasons why the knowledge-driven model employed by the CDC did not allow the agency to expand its domain consensus.