Attributes definition is a crucial, yet neglected topic of critical inquiry in the choice modelling literature. In a policy context, attributes should reflect public interests. However, guidance on how to go about achieving this criterion is lacking. To address this concern, we offer a novel approach to attribute definition – the knowledge base approach. A knowledge base is the particular ‘lens’ through which a shared understanding of a topic is gained (i.e. different groups of people view the world in different ways). Knowledge bases have been used in evidence-based policy to account for different sources of information and perspectives in complex policy settings, with the intention of improving policy and program development. The knowledge base approach was applied to the design of a choice experiment, specifically looking at conservation priorities for the waterways and wetlands in the Kimberley region of Western Australia. We conclude that the approach is both comprehensive and expedient, and could improve the selection of attributes for choice experiments that value policy or program change.