This book presents a theoretical treatment of externalities (i.e. uncompensated interdependencies), public goods, and club goods. The new edition updates and expands the discussion of externalities and their implications, coverage of asymmetric information, underlying game-theoretic formulations, and intuitive and graphical presentations. Aimed at well-prepared undergraduates and graduate students making a serious foray into this branch of economics, the analysis should also interest professional economists wishing to survey recent advancements in the field. No other single source for the range of materials explored is currently available.