If public health nursing is truly a synthesis of public health science and nursing science, then nurses must keep track of current developments in public health science. Unfortunately, the public health nursing literature has not kept pace with revolutionary developments in epidemiology, one of the sciences that informs population-focused nursing practice. Most epidemiology chapters in community health nursing texts do not reflect the intellectual development that has taken place in epidemiology over the past two decades. The purpose of this article therefore is to facilitate an updated synthesis by (a) reviewing the development of epidemiology and the focus of public health nursing practice through three historical eras, (b) discussing current controversies and tensions within epidemiology, (c) introducing an emerging paradigm in epidemiology based on an ecosocial perspective, and (d) discussing the congruence of this perspective with the evolving theory and practice of public health nursing.