This study tested the hypothesis that a volunteer experience would promote ego development for a sample of older adults. Current and non-volunteers were assessed on measures of personality and ego development before and after a 3-month baseline period, after six months of volunteering, and one year after completing their volunteer intervention. In addition, participants' perceptions of their volunteer experiences were assessed at this follow-up.  Repeated measures MANOVA measured the effect of the volunteering experience on ego development and demonstrated that ego development can change as a result of a volunteering intervention for a sample of elderly adults. The results showed that ego development scores for those individuals initially at the conformist or self-aware levels of ego development significantly increased as a result of the volunteer intervention, while ego development scores for those at the conscientious level or above remained stable. Participants' ego development scores did not change during the follow-up. Non-parametric analyses showed that of participants at the self-aware level and below, 49% increased in ego development. In contrast, only 17% of individuals at the conscientious level or above increased in ego development.  The present study supported the hypothesis that volunteering would have an impact on ego development for those at the lower levels of ego development, but not for those at the higher levels. These findings are consistent with previous research that points to a lack of growth in ego development above the self-aware level. This research has theoretical implications for the understanding of personality in older adults as well as of those experiences in adulthood that promote ego development