In the current globalized market, multinational corporations are experiencing heightened external social and environmental pressures to operate more responsibly. Transnational activist groups and advocacy NGOs are successfully framing normative expectations on corporate social responsibility and using tactics to name and shame socially and environmentally controversial corporations to pressure them to change their practices. An international norm of corporate social responsibility is increasingly shared by states, intergovernmental organizations and the private sector itself, and visibly emerging in the market place. Corporations engage with NGOs to demonstrate their conformance to the norm. The study explains why corporations engage with NGOs in different ways. It argues that corporations weigh the material incentives associated with the social and environmental consequences of their activities, and conform to the norm accordingly. They thus use the norm to further their material interests. Given that corporations are exposed to different levels of normative external pressures, there are different engagement strategies. In order to explain the terms under which corporations are likely to choose a particular kind of engagement strategy, a three-level concept of vulnerability is introduced. The more a corporation is vulnerable to the external normative pressures, the deeper it is willing to work with NGO/NGOs to ease that pressure. Hence, in NGO-business engagements, actors collaborate in order to gain the anticipated positive rewards of cooperation. They perceive those advantages greater than if they had pursued their goals separately.