Extending earlier research, this study explores individual (e.g. demographic and health characteristics), psychosocial (e.g. mastery and planning) and organizational factors (e.g. conditions of workforce exit) influencing retirement adjustment. Survey data were collected from 570 semi-retired and retired men and women aged 45 years and older. Findings suggest that higher income, and having better psychological and physical health accounted for better retirement adjustment. After controlling for the effects of demographics and health, a higher personal sense of mastery and more favorable conditions of exit significantly predicted adjustment to retirement. Pre-retirement planning was not related to retirement adjustment. However, analyses revealed that the effect of post-retirement planning on retirement adjustment was mediated by mastery. Practical implications for the design of interventions to promote mastery in later life and provide control over the transition from the workforce are discussed. (Contains 2 tables.)