The origins of this book lie in a series of training courses sponsored by the United Nations Environment Programme (Project No. FP/6108-88-01 (2855); 'Environment changes and the productivity of tropical grasslands'), with additional support from many international and national agencies. These intensive field and laboratory courses run for 3 weeks at a host institution in a developing country, with 25-30 trainees from the surrounding region. Photosynthesis provides the basis for all life since it drives the great cycles of CO2 uptake and 02 evolution. In order to benefit from these photosynthetic processes while main-taming the environment, we must under-stand photosynthetic mechanisms from the ecosystem level down to the primary reaction centres of membranes and enzymes.