Compensation payments to farmers who apply species-friendly farming activities are a common instrument to reconcile nature conservation with agriculture in Europe. In order to design cost-effective and ecologically effective compensation payments for conservation measures an ecologicaleeconomic modelling procedure has been developed using the example of protecting Large Blue butterflies. The modelling procedure forms the basis for the decision support tool EcoEcoMod. By comparing the effects of different mowing regimes on the butterfly populations for a given budget, the user can identify the cost-effective mowing regime and the corresponding compensation payments for that budget.