There are two traditions in the study of aging or, perhaps better, two sides of aging in the sense that aging is a natural life-long process, associated with illness, which unavoidably terminates with dying and death, but also that the process of aging is determined not only genetically but by environmental and behavioural circumstances. The conclusion is that a lifelong process can be optimized by extrinsic factors and even by those personal conditions determined by the transaction between intrinsic biological and extrinsic environmental factors, mediated always by behavioural conditions. In fact, during the last four decades, demographic and epidemiological data as well longitudinal, cohort, cross-sectional and experimental studies have yielded a new paradigm, variously called healthy, positive, optimal, productive, active or successful aging, which is considered a key issue at individual and population level from a scientific and socio-political perspective. After a review of several definitions of this view of aging and the description of the most important empirical studies of successful aging and related terms, as well as of the outcomes and determinants implied, problematic issues will be reviewed and we will finish by trying to disentangle the various factors specific to successful aging and other commonly considered equivalents by emphasizing that at the heart of this vision lies a focus on improvements in preventive medicine and the untapped potential of health promotion and illness prevention.