Continuity of patient care is an essential element of primary care because it should result in better quality care and disease management, especially for older adults who often have multiple chronic illnesses. Even though continuity of care has been studied for decades, it remains difficult to define and quantify and, there is no consensus about best practices for assessing whether or not a patient experiences it or a practitioner provides it. Moreover, no theoretically-driven measures for the assessment of continuity of care exist, and there have been few rigorous evaluations of its association with subsequent health and health service utilization outcomes. The principal purpose of this dissertation research was to better understand continuity of care for older adults by identifying the components of the patient-provider relationship that are important from the patient perspective, understanding how commonly used provider-proxy continuity measures relate to the patient experience, and evaluating whether the patient experience or provider-proxy assessments are associated with improved health and health services utilization. I used survey data from the 2,997 Medicare beneficiaries who participated in the 2004 National Health and Health Services Use Questionnaire (NHHSUQ) linked to their Medicare claims for 2002-2009. The NHHSUQ contained patient-reported data on usual primary provider, usual place of care, and the quality and duration of the relationship with their provider. By linking this information to their Medicare claims, I was able to evaluate both patient-reported and provider-proxy (claims-based) measures of continuity of care from two years prior to the survey, and evaluate the impact of continuity on health and health service utilization for five years after the survey. Study results indicate that the older adult patient experience of continuity is reflective of both relationship duration and patient-provider interaction during the care visit, and that most provider-proxy continuity assessments did not relate to patient perceptions. And, the patient and provider-proxy experiences of continuity had different relationships with important health outcomes. These results enhance our understanding of continuity of care for older adults and inform policymakers and researchers about aspects of continuity that are important for the health of older adults and the appropriate use of health care resources.