Olympe is a software developed by INRA, IAMM and CIRAD to model and simulate the functioning of cropping and farming systems. As it is based on economic analysis that considers contextual components, it enables identification and modelling of one or several farmers' strategies and trajectories. Prospective analysis is also possible, including prices volatility or climatic events and their impacts. This tool was first developed in close cooperation with research institutions involved in tropical agriculture and tested in different case studies, including agroforestry systems, in North and West Africa, Southeast Asia and Latin America, leading to a wide variety of applications. Such variety displays the richness that can be expected from reliable and representative farming systems studies at various levels. These levels go from the simple comparison between two cropping systems, through farming system modelling and further monitoring or counselling, to the study of entire irrigated schemes at regional levels, prospective analysis and elaboration of potential scenarios and role games. Such diversity in uses can be addressed to an equal diversity of actors: farmers, project or community leaders, extension institutions, researchers and policy makers.