The south-east Asian meeting was held in November 1979 in the Central Library of the Chiang Mai University, Chiang Mai, Thailand. Most of the papers presented at this workshop are included in these Proceedings. The fact that half of these are related to rice, emphasizes the importance of this food crop in the region. The paper by Watanabe et al. is listed first, as it gives a comprehensive review of existing data on the different aspects of nitrogen cycling in wetland rice. The following eight papers reflect the importance of dinitrogen fixation processes in a paddy field, although later papers stress the need for nitrogen fertilizers if high grain yields are to be achieved. The second half of the papers covers, appropriately, a wide variety of ecosystems such as forests, mangrove, rubber and oil palm. In addition, attention is given to nitrogen cycling in a catchment context, environmental problems associated with terrestrial nitrogen transformations, methods for studying nitrogen cycle processes under field conditions, and a modelling approach to nitrogen exchanges.