The adult life span is characterized as a time of divergent trajectories. It is a time of compounding losses (such as physical, sensory, and cognitive declines) and is also a time of surprising growth (such as improvements in well-being and emotion regulation). These divergent trajectories present theorists with the paradox of aging: in the face of accumulating losses, how is it that as people age, they generally feel good and experience greater well-being? Theorists have grappled with this paradox and have focused on how motivational, cognitive, control, and social factors impact emotional development across the adult life span. These foundational theories have paved the way to a deeper understanding of adult life-span development, but they do not draw as deeply from theories in affective science. Some of the latest perspectives on emotion and aging offer integrative views, such as how older adults may experience different discrete emotion (i.e., anger versus sadness) from an evolutionary functional perspective. Other perspectives consider how an array of appraisal processes may change across adulthood (such as shifts in evaluations of self-control versus other-control for younger versus older adults). These newer approaches dig deeper into mechanistic explanations and underscore the need for greater theoretical integration. Later life is clearly a time of increased well-being, but the field is only on the cusp of understanding the mysteries of emotional experience in later life.