Disciplinary psychology has failed to achieve a coherent conception of human agency. Instead, it oscillates between two differing conceptions of agency that are equally untenable: a scientistic, reductive approach to choice and action, and an instrumental approach that celebrates a romantic notion of free will. This book examines theoretical, philosophical psychology and argues for a historically and socioculturally situated human capacity for choosing and acting in ways not entirely determined by culture and/or biology. The authors present a detailed developmental theory of how agentic capability emerges from the pre-reflective activity of humans in a real physical and social world. Implications of the theory are considered for psychological research and practice, and for the broader socio-political impact of disciplinary psychology in Western liberal democracies.