The Bulletin summarises seed origin research in Sitka spruce over a period of 70 years. It provides a background to the ecology of the species, its introduction to Britain and the development and refinement of seed origin evaluation techniques. Phenological variation, particularly in relation to the potential for frost damage is described, height growth and basal area production are dealt with in depth, and current knowledge of variation in timber quality at the seed origin level is reviewed. The growth and production data are brought together in a new series of suitability maps of Great Britain with guidance to forest managers on their interpretation. Seed origin choice is considered with respect to the increasing availability of improved material from resulting from breeding work. Conclusions and recommendations are provided throughout the text. The Bulletin is an excellent resume of a major area of research by the Forestry Commission.