This chapter explores the characteristics and functions of TSMOs and the challenges that they pose to their targets via an analysis of their strategies, organization, mobilization, and outcomes. Most examples of TSMOs in the literature are based primarily in industrialized, developed countries, such as Greenpeace and Friends of the Earth (Wapner 1996; Tarrow 1996; 1998). However, the two TSMOs presented in this chapter are organized by indigenous actors and Amazonian activists and are based and develop their strategies in South American Amazonian countries. At first glance, it may seem unlikely that these resource-challenged actors could organize on such a grand scale. The mere fact that this has occurred makes the analysis of these TSMOs even more provocative.