This chapter describes the nature of acquired immune deficiency syndrome (AIDS) organizations as civil society actors. In theoretical terms, it is a critical appraisal of the theories of nonprofit organizations that provide us with insufficient answers to the question of what nonprofits are as a distinct sociological category. The chapter synthesizes existing research on AIDS organizations in the US and Germany in order to open up new perspectives on nonprofits. It describes the history of the field of AIDS organizing, how it emerged and evolved and which discourses were relevant. The study focuses on a specific kind of AIDS organization. Rather than on more radical and also better researched kinds of AIDS organizations, the focus will be on AIDS service organizations (ASOs). ASOs differ from their predecessors in that they have typically entered relatively stable relations with state agencies which provide more or less of their resources in exchange for fulfilling defined functions within public health policies.