Over the recent years, Business Process Management (BPM) paradigm has become more socially driven. The socialization of processes has become an unavoidable way to realize flexible processes by including means to improve collaboration, knowledge sharing and collective decisions. However, the majority of current proposed approaches are limited to the exploitation of social technologies (social networks, blogs, wiki…), without providing a coherent conceptual and reusable framework, independent from those technologies. This paper defines precisely the social dimension to be taken into account in BPM and recommends a set of models to structure the design and development of Social BPM. In addition, a social ontology has been developed with Protege 5.0 and rules for inferring knowledge and queries for exploiting it have been implemented with SWRL and SPARQL.