At every point in the lifespan, individual differences in a sense of control are strong predictors of motivation, coping and success and failure in a wide range of domains. What are the origins of these individual differences, how do they develop and what are the mechanisms by which they exert such an influence on psychological functioning? To answer these questions, this book draws on theories and research covering key control constructs, including self-efficacy, learned helplessness, locus of control and attribution theory. Skinner also considers such issues as: the origins of control in social interaction; environmental features that promote or undermine control; developmental change in the mechanisms by which experiences of control have effects on action; and the implications for intervening in competence systems - including interventions with people who are in uncontrollable circumstances.