The aim of this paper is to elicit the sensitivity of farmers to payments for agro-environmental services in a context of strong agro-ecological and policy constraints. We present results from a choice experiment survey performed among the whole population of agricultural decision-makers (104) in the Camargue area. Several econometric models have been estimated, the most significant being the Latent Classes one. The estimated parameters of the utility function, together with the parameter associated with the monetary attribute provided the monetary value of each relevant agro-ecological attribute and the associated outcomes (average and risk yield).