The outcomes of health interventions are co-constructed through negotiation between the competing knowledges of different stakeholders. In such a context, local implementing partners – who mediate between international donors/programme managers and local beneficiary communities – have a critical ‘knowledge brokering’ role to play. With appropriate support, they can facilitate integration of internationally established knowledge with local beliefs and practices in ways that support health-enhancing behaviour change. This paper focuses on the local field officers of an HIV prevention programme with Cambodian military couples. The paper asks: (1) what are the outcomes of knowledge encounters between international organizations and local field officers, as expressed in field officers’ interpretation of programme goals, strategies and messages? (2) To what extent does the intervention context support the field officers’ knowledge brokering efforts? Data collected includes semi-structured interviews, observations of programme meetings and activities, and textual materials. The findings demonstrate that field officers privilege international knowledge, particularly in interactions with international manager–partners. However, in the field, they both hybridize programme messages and struggle to resolve dilemmas provoked by conflicting international and local knowledges. Material and symbolic asymmetries within the intervention context are shown to undermine their knowledge brokering efforts, as field officers attempt to claim identities and futures as health development professionals. Implications for programme practices and accountability systems are discussed. Copyright © 2010 John Wiley & Sons, Ltd.