While public health, medical, government, and community actors agree that there is a serious asthma epidemic, there is significant disagreement over the role of outdoor environmental factors in causing or triggering asthma. The outcome of these disputes is important because it substantially influences the focus of public health prevention and government regulation. Minority communities in the United States have higher morbidity rates than white communities and, as a result, are more readily affected by debates over environmental factors and subsequent public health and government efforts. Therefore, asthma has figured prominently in community activists' agendas concerning health inequalities. We compare and contrast the efforts of two community environmental justice organizations that include asthma as part of their overall community organizing efforts. We explore obstacles and strategies common to both groups as well as key differences in their orientation vis-à-vis science. To do so, we first discuss the discovery, current research, community action, and resultant changes in the understanding of the disease, specifically within poor and minority communities. Then, to offer a context to examine our two examples of asthma activism, we explore the social discovery of asthma and its environmental correlates, along with the political and economic conflicts surrounding asthma research and regulation. Using examples from the two activist groups, we discuss common approaches to address asthma in poor and minority communities such as challenging "transit racism", employing an environmental justice perspective, and using education to empower community members. Finally, we explore how the issues raised in terms of asthma and the environment lead to a collective form of illness experience, in which people with asthma make direct links to the social determinants of their health.