This chapter provides an overview of the major issues involved with working memory. It deals with one of the popular theories of working memory, A. D. Baddeley's multicomponent model. The chapter examines the role of each part of working memory from this perspective and some of the memory phenomena associated with it. For Baddeley's multicomponent theory, working memory is made up of several components: the phonological loop, the visuospatial sketchpad, the episodic buffer, and the central executive. The central executive is the control center of Baddeley's model. Although each subsystem has some capacity, the central executive has additional capacity that it can devote to subsystem if the demands on it become taxing. The chapter also considers other views of what working memory is and how it operates, including N. Cowan's embedded processes model and R. W. Engle's controlled attention theory. In comparison, Cowan's embedded processes and Engle's controlled attention models eschew the idea that working memory is a separate system.