Life-span theory has long emphasized that cognitive functioning and well-being are key constituents of successful development and aging. There is mounting empirical evidence that these central domains of life are closely intertwined, with better performance on a number of cognitive ability tests going hand in hand with higher levels of well-being and satisfaction. Less well understood, however, are the multiple different sets of pathways that underlie how and why well-being either represents a consequence of cognitive functioning and development or operates as an antecedent condition thereof. The major objective of the current chapter is to provide a select overview of (1) an exemplary set of mechanisms that help explain the often dynamic and reciprocal links between the two major areas of life and (2) the role that several layers of individual and contextual factors play as resources and constraints. To do so, we proceed in four steps. First, we review conceptual considerations and empirical evidence on stability and change in well-being from mid adulthood to very old age, the vast individual differences in levels and rates of change, and how these differences are shaped by cognitive functioning and change. Second, we consider how well-being may serve as an antecedent of functioning and development of cognitive performance and abilities. Third, we present stress reactivity, health behaviors, social participation, and neurological pathways as some of the presumed underlying processes. Finally, we discuss the role that resources and constraints at individual and contextual levels may play for linking cognition and well-being.