Health department accreditation is one of the most important initiatives in the field of public health today. The Public Health Accreditation Board (PHAB) is establishing a voluntary accreditation system for more than 3000 state, tribal, territorial, and local health departments using domains, standards, and measures with which to evaluate public health department performance. In addition, public health department accreditation has a focus on continuous quality improvement to enhance capacity and performance of health departments in order to advance the health of the population. In the accreditation effort, a practice-based research agenda is essential to build the scientific base and advance public health department accreditation as well as health department effectiveness. This paper provides an overview of public health accreditation and identifies the research questions raised by this accreditation initiative, including how the research agenda will contribute to better understanding of processes underlying the delivery of services by public health departments and how voluntary accreditation may help improve performance of public health departments.