This volume presents the proceedings from the month-long program held at Johns Hopkins University (Baltimore, MD) on homotopy theory, sponsored by the Japan-U.S. Mathematics Institute (JAMI). The book centers on the following: classical and nonclassical theory of $H$-spaces, compact groups, and finite groups, classical and chromatic homotopy theory and localization, classical and topological Hochschild cohomology, elliptic cohomology and its relation to Moonshine and topological modular forms, and motivic cohomology and Chow rings. It surveys the current state of research in homotopy theory and suggests a framework for future developments. The book begins with two historical accounts, of the work of Professors Peter Landweber and Stewart Priddy, in honor of their sixtieth birthdays.