2013 Reprint of 1963 Edition. Full facsimile of the original edition, not reproduced with Optical Recognition Software. The theory of Boolean algebras is one of the most attractive parts of mathematics. On the one hand, Boolean algebras arise naturally in such diverse fields as logic, measure theory, topology, and ring theory, so that the study of these objects is motivated by important applications. At the same time, the theory which has been developed constitutes one of the most elegant parts of modern algebra. Finally, the subject still poses many challenging questions, some of which have considerable importance. A graduate student who wishes to study Boolean algebras will find several excellent books to smooth his way: for an introduction, the book by Halmos is probably the best of these monographs. It offers a quick route to the most attractive parts of the theory.