These volumes contain papers based on lectures presented at the conference, 'Algebraic Groups and Their Generalizations', held at Pennsylvania State University in July 1991. An outgrowth of the remarkable proliferation of Lie theory in the last fifteen years, this conference reflected both the diversification of technique in the classical theory and the beginnings of the study of new objects. These new objects include quantum groups and vertex operator algebras, as well as various kinds of infinite-dimensional groups and algebras inspired by new work in mathematical physics and quantum field theory. The first volume focuses on classical methods, while the second centers on quantum and infinite-dimensional methods. Each section begins with expositions and then turns to new results. This collection provides readers with an excellent introduction to these astonishing new mathematical worlds.