This chapter analyzes the participation of nonstate actors (NSAs) in contemporary UN treaty-making. It uses the Lasswell-McDougal-Reisman “seven decision functions” to understand the role played by NSAs at the various stages of treaty creation, negotiation, and implementation. It sets out four ways in which NSAs may participate in treaty-making: being at the table, on the sidelines, behind the scenes, and on the outside. The UN has established practices for accreditation and participation that have facilitated the increasing contribution of NSAs. Several key challenges remain, from risks to legitimacy to controversy over the involvement of industry and business interests.