The Indian Ocean nation of Madagascar is home to world-renowned levels of biological diversity, destructive trends of environmental degradation, and extreme poverty. International conversation action on the island has accelerated at a dramatic rate since the 1980s, including the implementation of a national environmental action plan, several debt-for-nature swaps, and more than a dozen integrated conversation and development projects. This article reviews the evolution of international involvement in Madagascar and develops a conceptual model to explain this recent explosion in activity. The model suggests that the environmental context of megadiversity and severe degradation, the growing global environmental movement, and the political-economic situation of Madagascar are the ultimate factors behind international conservation action. The particular timing of the conservation boom can be explained by the proximate factors of environmental research, 1980s environmentalism, and 1980s politics, facilitated by awareness, individual actors, group co-operation, and economic incentives. The results of the boom are tangible, with new protected areas, improved reserve management, and soil conservation programs. Yet criticism abound regarding impacts on local residents and wasted money. Many would agree it is too early to judge the success of the conservation boom.