The integration of clinical guidelines with office systems has great potential to improve population health. This article shows how simple office systems can be developed and applied to expand the impact of clinical guidelines on the health of populations of patients enrolled in managed care organizations, using diabetes as an example. The basic tools needed to improve population health include (1) clinical guidelines that clearly articulate important and specific health goals; (2) a clinical database that can identify patients who are eligible for guideline-recommended care, monitor this group of patients, and classify patients who need different levels of intervention; and (3) clinics that are organized in a way that facilitates provision of guideline-directed clinical care based on cues from the clinical database. This article illustrates a successful application of this strategy to improve the care of a population of patients with diabetes enrolled in health maintenance organization-owned clinics.