This monograph constitutes the first comprehensive investigation of reciprocal constructions and related phenomena in the world's languages. Reciprocal constructions (of the type The two boys hit each other, The poets admire each other's poems) have often been the subject of language-particular studies, but it is only in this work that a truly global comparative picture emerges. Nine stage-setting chapters dealing with general and theoretical matters are followed by 40 chapters containing in-depth descriptions of reciprocals in individual languages by renowned specialists. The introductory papers provide a conceptual and terminological framework that allows the authors of the individual chapters to characterize their languages in comparable terms, making it easy for the reader to see points of commonality between languages and constructions that have never been compared before. This set of volumes is an indispensable starting point and will be a lasting reference work for any future studies of reciprocals.