The health of Americans has improved drastically over the last century, as noted by the great increase in life expectancy (77 years in 2001 compared to 47 years in 1900) (McFalls, Jr., 2003). Advances in science, medicine, and living conditions have contributed to a shift from a focus on primarily infectious diseases to increased attention to chronic diseases. Thus, the focus for promoting the health of populations—the main objective of public health—calls for emphasis on community efforts at preventing and managing these lasting conditions (Aschengrau & Seage, 2007).

          Social work intersects with public health in many settings. As social workers, we are interested in the health and well-being of individuals and groups. Because we advocate for social justice, much of our work focuses on the health of disenfranchised groups. As social workers, we recognize that social factors contribute to disease; for example, inadequate access to care, environmental factors, poverty, and lack of education can lead to poor health. In order to lower suffering caused by disease and find ways to prevent disease, we must understand the causes of disease and identify the groups affected by specific diseases or problems.

          Epidemiology offers a method to systematically and quantitatively examine the social problems and diseases in which we are interested. This branch of public health seeks to identify the distribution of disease and understand its determinants. In public health social work practice, it is becoming increasingly important to use data to develop programs and interventions as well as to measure the outcomes of our efforts. Furthermore, public health social workers must be data literate in order to understand reports, studies, and evaluations to effectively work in interdisciplinary teams and to design and evaluate their own programs and interventions. Through epidemiological methods and the application of social epidemiology to our work, we can better understand illness and social problems, improve our interventions, and develop evidence-based policies and programs to prevent further disease.