With the advances in our knowledge about tree architecture, physiology of tree size control, development of dwarfing rootstcks and chemical growth retardants, many growers of temperate tree fruit crops have opted for closer planting of small sized trees. This system, popularly known as the high Density Planting (HDP), enables earlier croping, high regular yields and improved farm management practices, leading to higher productivity and profitability. High density planting in fruit trees was first introduced in case of apple in Europe during the nineteen sixties, with the development of Malling and Malling-Merton rootstocks. Subsequently, this was experimented in other temperate fruit corps like peack, plum, pear, and sweet cherry. The use of growth retardants, such as B-9, which restricts tree growth and encourages early flower induction, was also helpful for these high-density planting systems. The definition of 'High Density Planting' in our discussions has not been restricted to planting a higher number of trees of the same species per unit land area but to enlarge the scope to multi-species and multi-tier systems. After all, the ultimate aim is to produce more and more from unit area, may be form one species or from many, in order to make the venture of tropical fruit production more remunerative and sustainable. Therefore, mention of intercropping and multi species high-density orchards, as means to enhance cropping intensity and overall orchard productivity are also included in this book. Thus, the contents of the book reflect the current status and a critical analysis of our knowledge in the field of mono-and multi-crop high density planting in tropical fruit crop based farming.