Erikson's (1950) model of adult psychosocial development outlines the significance of successful involvement within one's relationships, work, and community for healthy aging. He theorized that the consequences of not meeting developmental challenges included stagnation and emotional despair. Drawing on this model, the present study uses prospective longitudinal data to examine how the quality of assessed Eriksonian psychosocial development in midlife relates to late-life cognitive and emotional functioning. In particular we were interested to see whether late-life depression mediated the relationship between Eriksonian development and specific domains of cognitive functioning (i.e., executive functioning and memory). Participants were 159 men from the over-75 year longitudinal Study of Adult Development. The sample was comprised of men from both higher and lower socioeconomic strata. Eriksonian psychosocial development was coded from men's narrative responses to interviews between the ages of 30-47 (Vaillant & Milofsky, 1980). In late life (ages 75-85) men completed a performance--based neuropsychological assessment measuring global cognitive status, executive functioning, and memory. In addition depressive symptomatology was assessed using the Geriatric Depression Scale. Our results indicated that higher midlife Eriksonian psychosocial development was associated with stronger global cognitive functioning and executive functioning, and lower levels of depression 3 to 4 decades later. There was no significant association between Eriksonian development and late-life memory. Late-life depression mediated the relationship between Eriksonian development and both global cognition and executive functioning. All of these results controlled for highest level of education and adolescent intelligence. Findings have important implications for understanding the lasting benefits of psychosocial engagement in mid-adulthood for late-life cognitive and emotional health. In addition, it may be that less successful psychosocial development increases levels of depression making individuals more vulnerable to specific areas of cognitive decline.