Data are presented for the duration and amount of growth of the leading shoots of twenty-five species of conifer during four to six seasons and, for a further eighteen species, the mean duration of growth for one to seven seasons. Curves of growth derived from weekly measurements show the patterns of growth typical of some genera. All data refer to a single site in south-west Surrey. Four patterns of growth are distinguished. Species with very small resting buds have long periods of growth and those with large buds have short periods. There are two intermediate growth patterns and one of these, shown most clearly by the larches ( Larix spp.), combines in some measure the advantage of each extreme and shows the greatest potential growth. The greatest annual growths noted in Britain have occurred in individual species of all four patterns, however, and the rate of elongation of the shoot is as important as the period or pattern of growth. In the small sample studied, there was little variation within species in the date on which growth began but great variation in the date on which it ceased. Trees suffering from check, suppression, or disease begin at the normal time, but elongate slowly and stop growing very early. The species which begin growth early in the season show wider variation in their date of starting from year to year than those which begin late. An analysis was also carried out to determine the relationship between length of shoot, period of growth, and some climatic factors. The samples were too small for results of high significance.