Cognitive framing theories explain how individuals understand and apply information in relation to existing experiences and beliefs. Yet these theories have rarely been applied to explore the interpretation and application of evidence in policy development. This paper undertakes a critical discourse analysis of interviews and texts surrounding a highly contested United States policy for international HIV prevention. Analysis illustrates that, rather than speaking for itself, evidence is defined by framing processes, with competing interpretations found to reflect internal consistency with core beliefs about sexual behaviour. This illustrates the importance of making explicit the roles that belief systems play in shaping how evidence is used in policy development.