Addressing asthma from a public health perspective is a relatively new concept for which the literature provides little guidance. A public health approach seeks to decrease the burden of asthma and improve health outcomes at the population level, such as communities, cities, or states, by reaching large numbers of individuals with effective interventions and at reasonable cost. Projects designed to achieve a measureable impact at the population level are fundamentally different from projects or interventions designed to improve outcomes among individuals. This paper uses the experience of the Controlling Asthma in American Cities Project and a review of the relevant literature to explore some of the unique questions and considerations that are implicit when planning large-scale asthma projects intended to improve population outcomes. The paper is intended to inform decision making by local and state government agencies, managed care organizations, health systems, community coalitions, and funders. Analysis of asthma and other chronic disease projects aiming to achieve population-level impact is an area for continued public health research.