The influence of for-profit businesses in collective action across countries to protect and promote population health dates from the first International Sanitary Conferences of the nineteenth century. The restructuring of the world economy since the late twentieth century and the growth of large transnational corporations have led the business sector to become a key feature of global health politics. The business sector has subsequently moved from being a commercial producer of health-related goods and services, contractor, and charitable donor, to being a major shaper of, and even participant in, global health policymaking bodies. This chapter discusses three sites where this has occurred: collective action to regulate health-harming industries, activities to provide for public interest needs, and participation in decision-making within global health institutions. These changing forms of engagement by the business sector have elicited scholarly and policy debate regarding the appropriate relationship between public and private interests in global health.