Public health agencies increasingly are recognizing the need to formally and quantitatively assess and improve the quality of their programs, information, and policies. Measuring quality can help organizations monitor their progress toward public health goals and become more accountable to both the populations they serve and policy makers. Yet quality assessment is a complex task that involves precise determination and specification of useful measures. We discuss a well-established conceptual framework for organizing quality assessment in the context of planning and delivery of programs and services by local health departments, and consider the strengths and limitations of this approach for guiding quality improvement. We review several past and present quality measurement-related initiatives designed for public health department use, and discuss current and future challenges in this evolving area of public health practice.