The purpose of the current study was to evaluate short- and long-term effects of group reminiscence on agitated symptoms and quality of life (QOL) for individuals with dementia. A quasi-experimental study using a repeated-measures design was conducted in 43 residents with dementia. Participants received a 50-minute group reminiscence therapy session once per week for 10 weeks. Outcomes were measured 1 week before, 1 week after, and at 3 months postintervention. Results showed no significant difference on the overall agitated behavior of participants. However, verbally aggressive behavior decreased significantly (p = 0.025), whereas intentional falling (p = 0.025), hoarding (p = 0.021), and akathisia (p = 0.027) significantly decreased in the short term. Participation in group reminiscence therapy significantly improved QOL (p < 0.001) across time periods for individuals with dementia. The findings provide information for professional and nonprofessional caregivers of individuals with specific agitated behaviors to improve their QOL. [Journal of Psychosocial Nursing and Mental Health Services, 57(8), 30-36.].