A brief account is given of the evolution of the concept of working memory from a unitary store into a multicomponent system. Four components are distinguished, the phonological loop which is responsible for maintaining speech-based information, the visuospatial sketchpad performing a similar function for visual information, the central executive which acts as an attentional control system, and finally a new component, the episodic buffer. The buffer comprises a temporary multidimensional store which is assumed to form an interface between the various subsystems of working memory, long-term memory, and perception. The operation of the model is then illustrated through an account of a research programme concerned with the analysis of working memory in Down syndrome.