Two agricultural development projects based on cons ervation agriculture and agriculture/livestock integration are implemented i n Madagascar with both a “watershed approach” and a “farming system approach”: the BV-l ac project in the area of Lake Alaotra and the BVPI-SEHP project in Vakinankaratra (Central hi ghlands) and South-East. A farming systems reference monitoring network (FSRMN) has be en set up with two objectives: i) to help the project in decision making processes for choosi ng appropriate technologies that will be developed according to a farmer’s typology using pr ospective analysis, ii) to monitor the project’s economical impact in the short and medium term. The farming system modelling approach is based on a software developed by INRA-C IRAD-IAMM (“Olympe”, JM Attonaty, INRA), The approach is based on partnership (smallh older, farmers’ organizations, project operators and local administration), farming system analysis, and modelling for a Decision Support Systems (DSS) project orientation. Adoption of conservation agriculture (CA) represents both a real change of paradigm for local farmers and a real challenge for agriculture and natural resources sustainability