Baddeley and Hitch's (1974) Working Memory (WM) model is one of the most widely known and enduring concepts in cognitive psychology. It describes a set of modules dedicated to the time-limited storage and manipulation of information. A wealth of experimental data from cognitive psychology, neuropsychology and neuroimaging research has supported the model, and it has been practically applied in numerous fields, particularly educational and clinical psychology. WM is reduced in numerous neurological, psychiatric and developmental conditions, and WM functioning is reliably associated with various facets of everyday functioning. The measurement of WM for clinical purposes is a fundamental component of a neuropsychological assessment, as working memory overlaps with or underpins functioning in many other domains of cognition and emotion. Recently, the prospect of improving WM through computerised adaptive training has attracted extensive funding and research efforts across paediatric, adult and ageing populations. The hope is that by targeting the fundamental processes that make up WM, generalised benefits will ensue. However, there is a lack of consistent evidence that training-related benefits generalise even to performance on tests of related cognitive functions, let alone improvements in daily function. Hence, caution should be exercised in employing such training approaches. The clinical message is to assess and intervene with WM only as part of a holistic formulation and in relation to functional goals. Note that material presented in the chapters on attention (see Chapter 14) and executive functions (see Chapter 17) is highly relevant to understanding and working with WM in both applied and research settings, as is the section on ‘brain training’ in the chapter on innovative approaches in rehabilitation (Chapter 34).