Cambridge Social Ontology is among the longest running continuous research projects in economics and philosophy. Building on a critique of the modern mainstream of economics and its insistence on the use of mathematical modelling, the project emphasises the importance of social ontology – the study of the nature and basic structure of social reality – for both economics and the social sciences more generally. In this paper, I explore the context in which this project has developed. I begin with a discussion of the history of the project and its development through meetings of the Cambridge Realist Workshop and, more recently, the Cambridge Social Ontology Group. I then explore the relationship between Cambridge Social Ontology and two different philosophical approaches, critical realism – most notably the work of Roy Bhaskar – as well as with analytic approaches to social ontology and, most importantly, the work of John Searle.