The following article makes a case for the social sciences to renew their interest in systems, drawing on ideas circulating in organisational and community psychology, industry, engineering, biology and ecology, the new physics, management, evaluation, religion and spirituality, policy-making, human services professions, and service-user and community movements. It charts a different kind of systemic thinking in striking contrast to traditional mechanistic social systems theory. Sociology’s current resiling from systems theory is explained as a legacy of its loyal service in the ‘battlefield’ of the post WW2 critique of authoritarian structural-functionalist positivist systems and the hard-won interpretive turn to issues of process, diversity, conflict, change and a critical and ‘qualitative’ epistemology. A new transdisciplinary mental architecture of self-organising processes for complex living systems is offered which integrates understandings of both ‘structural systems’ and the ‘processual systemic’ in individual psychology, organisational sociology, and in action research as its epistemology.