The concept of social structure, present in social ontology since the 19th century, hasbeen used in various, not always clearly specified, meanings. The present use of the concepthas been decisively influenced by the elaborations in the hands of the so-called “newstructuralists” of the 1970s: Pierre Bourdieu, Roy Bhaskar and Anthony Giddens. To understandthe contemporary developments, it is necessary to be acquainted with its formative influences.In the paper, we compare the approaches of Bhaskar and Giddens, especially in the context oftheir mutual (...) compatibility and the challenges facing anyone wanting to develop their ownconcept of social structure based on the elaborations of the concept by Bhaskar and Giddens.The most fundamental issues appear to be especially the mode of existence of social structures,the heterogeneous character of different kinds of social structures, and the transition from theontology of the natural world to that of the social world by Bhaskar. (shrink)