The aim of the paper is to introduce corporate social responsibility CSR as an organisation’s management and stakeholders’ relations tool in post-communist countries for ensuring the organisation’s social legitimacy. The article discusses how understanding the interdependence between the organisation and society helps to support the organisation to develop social legitimacy and therefore ensure its sustainability. The general research problem in this article is connected with the societal context of studied organisations: how CSR could be positioned and managed in a post-communist society to avoid a rebuff against an organisation’s CSR activities. The topic of this paper is approached through three research questions: how post-communist organisations see the CSR position in the organisation, how social legitimacy is acknowledged and defined, and finally to what extent CSR is seen as a tool for ensuring social legitimacy. For the research, seven Estonian organisations’ representatives with management responsibility were interviewed to find out their thoughts and ideas about CSR and social legitimacy.