Research on individual differences in attachment—and their links to emotion, cognition, and behavior in close relationships—has proliferated over the last several decades. However, the majority of this research has focused on children and young adults. Little is known about mean-level changes in attachment orientation beyond early life, in part due to a dearth of longitudinal data on attachment across the life span. The current study used a Q-Sort-based measure of attachment to examine mean-level changes in attachment orientation from age 13 to 72 using data from the Block and Block Longitudinal Study, the Intergenerational Studies, and the Radcliffe College Class of 1964 Sample (total N = 628). Multilevel modeling was employed to estimate growth curve trajectories across the combined samples. We found that attachment anxiety declined on average with age, particularly during middle age and older adulthood. Attachment avoidance decreased in a linear fashion across the life span. Being in a relationship predicted lower levels of anxiety and avoidance across adulthood. Men were higher in attachment avoidance at each point in the life span. Taken together, these findings provide much-needed insight into how attachment orientations change over long stretches of time. We conclude with a discussion about the challenges of studying attachment dynamics across the life course and across specific transitions.