The World Health Organization (WHO) defines health as a "state of complete physical, mental and social well-being and not merely the absence of disease or infirmity." Despite general acceptance of this comprehensive definition, there has been little rigorous scientific attempt to use it to measure and assess population health. Instead, the dominant model of health is a disease-centered Medical Model (MM), which actively ignores many relevant domains. In contrast to the MM, we approach this issue through a Comprehensive Model (CM) of health consistent with the WHO definition, giving statistically equal consideration to multiple health domains, including medical, physical, psychological, functional, and sensory measures. We apply a data-driven latent class analysis (LCA) to model 54 specific health variables from the National Social Life, Health, and Aging Project (NSHAP), a nationally representative sample of US community-dwelling older adults. We first apply the LCA to the MM, identifying five health classes differentiated primarily by having diabetes and hypertension. The CM identifies a broader range of six health classes, including two "emergent" classes completely obscured by the MM. We find that specific medical diagnoses (cancer and hypertension) and health behaviors (smoking) are far less important than mental health (loneliness), sensory function (hearing), mobility, and bone fractures in defining vulnerable health classes. Although the MM places two-thirds of the US population into "robust health" classes, the CM reveals that one-half belong to less healthy classes, independently associated with higher mortality. This reconceptualization has important implications for medical care delivery, preventive health practices, and resource allocation.comprehensive health | aging | disease | well-being | health policy I n 1946, the World Health Organization (WHO) defined health as "a state of complete physical, mental and social well-being and not merely the absence of disease or infirmity" (1). In 1977, George Engel (2) built on this definition, calling for a new biopsychosocial model. It integrated traditional medicine with psychosocial factors, which stimulated the field of psychosomatic medicine. These ideas have been honored more as an ideal than in practice.Here, we seek to apply this comprehensive definition to characterize the health of US older adults living in their homes. Studying a representative sample of the US population ages 57-85 y old [the National Social Life, Health and Aging Project (NSHAP)], we gathered wide-ranging information on the diseases of the traditional "Medical Model" (MM) and also, psychological well-being and physical function in a "Comprehensive Model" (CM) informed by the approach by Engel (2, 3). We empirically determined if these health measures formed distinct constellations, characterizing groups of people with different patterns of health and well-being. Our large survey of 3,005 community-dwelling older adults ages 57-85 y old was not a clinical sample or a sample of con...