The second edition of The Chemistry of Soils, published in 2008, has been used as a main text in soil-science courses across the world, and the book is widely cited as a reference for researchers in geoscience, agriculture, and ecology. The book introduces soil into its context within geoscience and chemistry, addresses the effects of global climate change on soil, and provides insight into the chemical behavior of pollutants in soils. Since 2008, the field of soil science has developed in three key ways that Sposito addresses in this third edition. For one, research related to the Critical Zone (the material extending downward from vegetation canopy to groundwater) has undergone widespread reorganization as it becomes better understood as a key resource to human life. Secondly, scientists have greatly increased their understanding of how organic matter in soil functions in chemical reactions. Finally, the study of microorganisms as they relate to soil science has significantly expanded. The new edition is still be comprised of twelve chapters, introducing students to the principal components of soil, discussing a wide range of chemical reactions, and surveying important human applications. The chapters also contain completely revised annotated reading lists and problem sets.