Given the broad scope and intersectoral nature of public health structures and practices, there are inherent difficulties in defining which services fall under the public health remit and in assessing their capacity and performance. The aim of this study is to analyze how public health functions and practice have been defined and operationalized in different countries and regions around the world, with a specific focus on assessment tools that have been developed to evaluate the performance of essential public health functions, services, and operations. Our review has identified nearly 100 countries that have carried out assessments, using diverse analytical and methodological approaches. The assessment processes have evolved quite differently according to administrative arrangements and resource availability, but some key contextual factors emerge that seem to favor policy-oriented follow-up. These include local ownership of the assessment process, policymakers' commitment to reform, and expert technical advice for implementation.