This thesis examines the practices and effects of participatory citizenship projects geared toward incorporating members of poor rural communities—particularly women and ethnic minorities—into an emerging regional apparatus based on “community-based disease surveillance,” expanded veterinary extension services, and the promotion of “pro-poor,” market-oriented incentives for household and community management of animal diseases. The dissertation focuses on transnational efforts to control emerging infections in the Greater Mekong Subregion (GMS), focusing on the particular predicaments of Cambodia and Laos. Regional integration in the GMS since the 1990s has made trading partners out of ancient enemies, but it has also created a new set of problems related to food security, commercial and illicit livestock trade, ecological transformations, and emerging infections. In particular, recent outbreaks of foot-and-mouth disease (FMD) and the H5N1 strain of highly pathogenic avian influenza (HPAI-H5N1) in Southeast Asia have created a situation where the same types of animals promoted by the Food and Agriculture Organization of the United Nations (FAO) to alleviate poverty and increase food security in the region are now also viewed as biological reservoirs for intolerable threats to “global” human health and industry. The project is based on multi-sited ethnographic fieldwork conducted between October 2006 and March 2009 with two groups of participants who have different relationships to animal disease control activities in the region: (1) professional experts working with FAO and its state and nongovernmental partners and (2) backyard farmers, livestock buyers, community leaders, and village animal health workers who have participated in FAO projects to control emerging infections. Using ethnographic documentation of local dilemmas and comparative examples from different contexts (national as well as urban versus rural), the dissertation evaluates how transnational endeavors to control emerging infections are transforming institutional milieus, national regimes of health government, and political relations between citizens, communities, and the state in the region.