Growth is the biological phenomenon of increase in size with time. The sudden increase in tree diameter often observed after rain is not due to growth but reflects the effects of bark swell. The relationships of tree size to age and increment to age are also important to the forester particularly in predicting future growth. In any one growing season, different parts of a tree start growing at different times. Different species may also react differently. Generally, height growth precedes any diameter growth or needle flush. The progression of terminal bud extension (main stem and branches) is basipetally, i.e. extension growth starts at the top of the tree and progressively moves downwards towards the base. The amount of height growth in any one season depends on hereditary factors, immediate past environmental conditions and present environmental conditions. Diameter growth also proceeds basipetally and is much more related to current foliage and present environmental conditions. The book presents the most up-to-date research in the field.