This paper presents the results of a research aimed at explaining the system of interactions of social actors in Public Communication of Science and Technology (PCST), in the context of a social web defined by the novel systems of communication sustained on informational and communication technologies. The study’s theoretical framework highlights the strategic importance of a Public Communication  which focuses on promoting public appropriation of Science and Technology, going beyond the role of Journalism and Science Communication that informs a qualified public, to one that stablishes a bond with policies and decision making in the area, made with participation of international agencies, governments, producers of science and technology, journalists’ associations, educational institutions, and citizens. The research relies on Explicative Methodology. A revision of pertinent bibliography leads to the conclusion that the system of social interactions mediated by personal, interpersonal and grupal global communications, define the relationships in the communicational exchange of the social actor with regard to public communication of science and technology and policies aimed at its appropriation.