The University of Wisconsin Population Health Institute and the Robert Wood Johnson Foundation (RWJF) released their annual County Health Rankings this week, assessing the overall health of nearly every county in all 50 states and in the District of Columbia (www.countyhealthrankings.org). The County Health Rankings use standard measures to rank health status, with consideration of health outcomes (length and quality of life) and health factors (determinants of health). The health factors are categorized by health behavior, clinical care, social and economic factors, and physical environment. (Read about UW’s method for weighting these health factors and for collecting county level data from national and state data sources on their website.) Advocates of rankings see them as a “call to action”—a valuable tool that can be used by communities to reflect upon their rank, examine their current policies, and seek opportunities for policy and systems change. According to the Wisconsin Population Health Institute, some communities have been able to successfully mobilize for change since the launch of the Rankings in 2010, including Wyandotte, Kan.; Hernando, Miss., and the Joy-Southfield neighborhood in Detroit. Though the Rankings may be a catalyst for change, Rankings Director Bridget Booske Catlin points out that there has been little movement among the highest and lowest ranked counties, demonstrating that moving the needle on the determinants of health is a tremendous task. Among the research community, there is some concern about the methodological challenges that underlie these analyses and the ease with which the media and public can misinterpret the results. AcademyHealth’s PHSR Interest Group hosted a policy breakfast discussion on strengths and limitations of rankings, as well as suggested questions that policymakers, the press, and the public should ask when interpreting the results. A recording of that discussion is available online. There is no doubt that these Rankings provide an opportunity for research, particularly for the growing field of public health systems and services research (PHSSR). The Rankings are becoming a frequently used data set for PHSSR, especially reliable as the measures remain consistent over time (though UW continues to add new measures as well). Also, public health services and systems researchers are increasingly looking to expand the evidence base for effective decision-making in public health practice and policy through research that utilizes natural experiments. The Rankings themselves and the community response to them in particular, provide fruitful opportunity for analysis. (AcademyHealth’s PHSR Interest Group recently hosted a methods webinar on analyzing natural experiments, which is available for free in our professional development catalog.) Congratulations to the University of Wisconsin Population Health Institute for their hard work in producing the Rankings, for their continued effort promoting the factors that contribute to health, outside of the health care system, and for producing a valuable tool for the research community.