Quality improvement in public health is a key element in the movement toward accreditation. Multiple national, state, and local initiatives are under way to define quality in a public health context and to develop tools and promising practices to support quality-improvement efforts in local health departments. Until recently, efforts to improve quality at the local level have largely focused on performance measurement to assess the relationship between inputs, outputs, and outcomes. The Los Angeles County Department of Public Health has developed its own unique approach to quality improvement. This approach includes focusing on three overlapping areas (professional practice, performance improvement, and public health science) that align closely with essential public health services 8 (competent worker), 9 (evaluation), and 10 (research). Broadening the focus of quality-improvement efforts to include these three areas (rather than performance improvement alone) provides additional opportunities to address key infrastructure issues that may affect the quality of services that are provided to the public and, thus, health outcomes. While the experience in Los Angeles County parallels other efforts, it includes unique elements that will be of use to public health professionals in other agencies.