Book excerpt: This book presents an up-to-date view of theories, practical methods and applications of solvent effects and chemical reactivity in condensed phases. Subjects treated include continuum solvation models, the theoretical basis for the treatment of solvent effects in density functional theory, Monte Carlo simulations of chemical reactions in solution, DFT molecular dynamics simulations, crossing the transition state in solution, valence bond multi-state approach to chemical reactions in solution, quantum theory of solvent effects and chemical reactions. The approaches taken as well as the resulting findings are discussed in detail, thus covering a large part of the methodology currently used in this field. Audience: This volume will be useful to graduate students in chemistry, physical chemistry and biochemistry, to research workers with a background in quantum chemistry and quantum mechanics, to pure and applied quantum chemists, and to industrial molecular modellers.