At the end of the 1990s, Brazil was faced with a potentially explosive HIV/AIDS epidemic. Through an innovative and multifaceted campaign, and despite initial resistance from multinational pharmaceutical companies, the government of Brazil was able to negotiate price reductions for HIV medications and develop local production capacity, thereby averting a public health disaster. Using interview data and document analysis, the authors show that the exercise of corporate social responsibility can be viewed in practice as a dynamic negotiation and an interaction between multiple actors. Action undertaken in terms of voluntary CSR alone may be insufficient. This finding highlights the importance of a strong role for national governments and international organizations to pressure companies to perform better.