Comprehensiveness is a key element of primary care and is highlighted in several national primary care transformation initiatives. It has been defined as the extent to which a patient’s primary care provider (practitioner, practice, or team) recognizes and meets the large majority of the patient’s physical and common mental health care needs, including prevention and wellness, and acute, chronic, and comorbid condition management. This concept invokes several aspects of patient care. These include the depth and breadth of conditions managed by the primary care practitioner (PCP), as well as the extent to which the PCP can effectively address the many relatively common problems their patients may experience. Recently, Medicare claims have been used to develop reliable and valid measures of these two dimensions of primary care comprehensiveness.