The symposium In the next decades, agriculture will have to cope with an ever-increasing demand for food and raw basic materials on the one hand, and with the necessity to use resources without further degrading or exhausting the environment on the other hand, and all this within a dynamic framework of social and economic conditions. Intensification, sustainability, optimizing scarce resources, and climate change are among the key issues. Organized thinking about future farming requires forecasting of consequences of alternative ways to farm and to develop agriculture. The complexity of the problems calls for a systematic approach in which many disciplines are integrated. Systems thinking and systems simulation are therefore indispensable tools for such endeavours. About 150 scientists and senior research leaders participated in the symposium ‘Systems Approaches for Agricultural Development’ (SAAD) at the Asian Institute of Technology (AIT), Bangkok, Thailand, in December 1991. The symposium had the following objectives: - to review the status of systems research and modeling in agriculture, with special reference to evaluating their efficacy and efficiency in achieving research goals, and to their application in developing countries; - to promote international cooperation in modeling, and increase awareness of systems research and simulation. The symposium consisted of plenary sessions with reviews of major areas in systems approaches in agriculture, plus presentations in two concurrent sessions on technical topics of systems research. Subjects of studies were from tropical and temperate countries.