Acidification of forest soils is one of the major problems facing forestry throughout many regions in the world. The adverse properties brought about by acidification and encountered by trees are essentially the same as those faced by crop plants, i.e., low availability of base cations and high loading of Al on the soil cation exchange system [1]. However, the longevity of forest systems, where even in intensively managed plantations the rotation time may be in excess of 40 years and in more natural forests over 120 years, poses a number of specific problems. The aim of this chapter is not to discuss in depth the causes and effects of acidity on forest ecosystems, but rather to discuss the difficulties and implications of trying to manage soil acidity in forest soils.