This paper proposes a preliminary conceptual framework designed to support strategic decisions about which crop populations-in a well-defined reference area within a crop's center of diversity-are suitable candidates for ex situ and on-farm conservation. It is assumed that the reference area has already been identified based on prior beliefs about its relative importance among other potential conservation areas. The framework draws on aspects of characteristics models and on the theory of impure public goods. It enables us to begin answering questions about how breeding interventions and policy incentives affect farmers' variety choice and about how variety choice, seed flows, and seed selection affect genetic diversity. The framework can be applied to the choice of conservation strategies in a reference question, using utility index to present value in current use and using genetic distance as a proxy for evolutionary potential. The application of the framework can be directly interpreted in terms of the relative costs of alternative conservation strategies. To provide a more dynamic view of farmer management of diversity, the framework can also be used to investigate how changes in the exogenous technical, socioeconomic, and cultural parameters that condition farmers' decision influence the array of varieties they maintain. The relative importance of factors measured at different scales can also be tested (e.g., variety characteristics, household characteristics). In this way, the framework can help develop policy recommendations to support on-farm conservation of genetic resources. Even so, it is important to recognize that in some cases changes in exogenous environmental and socioeconomic factors may be so overwhelming that farmers' incentives to maintain varieties will disappear, despite substantial efforts to make them attractive.24 pages