The Growth Processes activity had four participating countries, Finland, Sweden, UK and USA. The overall objective of the activity was to investigate growth processes of greatest importance in species used and leading to improvement and sustainability in short rotation forestry biomass production. The areas of interest agreed by the participants as topics for further research and information exchange were: canopy dynamics, mixed clonal plantations, coppice biology with root/shoot interactions, water-use efficiency in coppice and growth models of coppice growth processes and systems. The activity arranged four meetings during four years, each with a separate theme in agreement with the programme of work. The meetings were joint meetings with other IEA-activities and also with other organisations such as FAO/IPC and IUFRO. A number of scientific presentations from the activity meetings were published in peered journals. A separate study on water-use efficiency and drought tolerance in selected willow clones was undertaken in co-operation with the University of Toronto. A research collaboration on translocation of nutrients and carbon allocation in coppice was carried out with the USDA Forest Service in Rheinlander, WI., USA to provide data for a growth model of physiological processes in coppice systems presently under development as an international/IEA co-operation project. Two literature reviews have also been carried out, one dealing with the importance of reserve nutrients for resprouting in willows and the other reviewing existing growth models of fast-growing trees that served as a basis for a modelling workshop held as a joint meeting of this activity, SUAS and New Cultural Treatments and Yield Optimisation activity.