While aging is associated with increased health problems and disability, most seniors subjectively rate their health positively, and view aging as a positive period of life evaluation, increased wisdom and maturity. The somewhat paradoxical nature of these findings suggests that later life well-being is multidimensional and variable. Drawing on data from a nationally representative survey, this paper describes the subjective well-being of a sample of Canadian seniors, using the Ryff multidimensional measure of well-being, and investigates the effects of various demographic, health and socio-economic conditions on reported levels of well-being. Seniors’ well-being is robust in terms of the dimension of autonomy, which is resilient to the physical and social circumstances of later life. But, as seniors age, they experience declines in their sense of purpose in life and opportunities for personal growth, in part, due to socio-economic factors. Good health and functional status are important for seniors’ sense of mastery over their surrounding world.