"Acid sulfate soils are endemic in the low-lying coastal regions ofSoutheast Asia. The soils are characterized by the presence of mineral pyrite (FeS2), formed in the sediments under reducing conditions when sea level in the region rose to 3-5 meters above the present height some 4300 years BP. Later on in the geological history, the said areas became new land that can be utilized for agriculture or otherwise when the sea dropped to the current level. When the flooded land is reclaimed for agriculture, pyrite in the sediments is exposed to the atmospheric conditions and oxidized, releasing high amount of acidity to the environment that affect crop growth and aquatic life in the vicinity. In the end, a new mineral called jarosite is formed. If this straw-yellow mineral is seen in the soil profiles, the soil reaction is very acidic. Beside low pH stress, crop growth and/or production is significantly affected by Al and Fe toxicity. For all intents and purposes, acid sulfate soils are unsuitable for crop production, unless their problems are alleviated via agronomic means presently available at hand. This books entitled “Acid Sulfate Soils in Southeast Asia: Occurrence, Properties and Management” is written to describe and discuss the formation of the soils, starting with the mineralization of pyrite under reducing environment and ending with its oxidation due to exposure to the atmosphere because of drainage. The next part of the book explains in detail the physico-chemical properties of acid sulfate soils, having in mind to classify them for the purpose of technology transfer across the globe. The final part deals with soil reclamation to sustain crop production in the long run. Recent advances in agricultural innovations or agro-technology packages obtained from research conducted on acid sulfate soils in Southeast Asia over the years, particularly in Malaysia, are highlighted. The crop discussed in this book are those common in the region, especially Malaysia - rice, oil palm and cocoa. "