Physical, mental and social components of wellbeing are known to be important to health. However, in health research and practice much of the focus has been on physical and mental wellbeing with less attention paid to social components, which we assert detrimentally affects the development of health policies and practices. A systematic measure of wellbeing, which captures both mental (internal) and social (external) wellbeing is needed to offer a richer, nuanced, and more complex multi-dimensional account of wellbeing. We report on using Group Concept Mapping (GCM) to define a social conception of wellbeing. The aim was to capture the complex multi-dimensional aspects of the ‘social resources’ that people access, and the ‘social worlds’ they inhabit. We highlight why it is necessary to separate and promote different components of wellbeing simultaneously, and why a multi-dimensional definition of social wellbeing is needed. We discuss the importance of promoting social wellbeing in health and social care settings, with reference to social prescribing. The paper demonstrates how a theoretically coherent and workable conception of social wellbeing may support scale development i.e., the South Wales Social Wellbeing Scale (SWSWBS). It is anticipated that such a tool would measure the quality of respondents’ overall experience of social wellbeing via the external social resources they possess, their perceived ability to engage in and enjoy the social world in which they live, and, as a result, their capacity for human functioning and flourishing.