Aging is an important part of all human life. It is the last stage of human life, and they become weaker from a physical perspective as well as more sensitive and emotional from a psychological perspective. The aim of this reminiscence therapy is to improve the self-esteem and mental well-being of senior citizens. The aim of the study was to evaluate the effectiveness of reminiscence therapy on self-esteem and mental well-being among senior citizens residing in selected convalescent homes in the Kanyakumari district of Tamil Nadu. The design used in this study is quasi-experimental with a pretest posttest control group design. The study is conducted in St. Joseph Old Age Home and Anbaham Old Age Home. The tools used were the Rosenberg self-esteem and the Warwick Edinburgh mental well-being scale. Findings revealed that among experimental group the pretest mean self-esteem score was 11.70, and the mental well-being score was 36.06. The post-test mean self-esteem score was 21.13, and the mental well-being score was 61.00. Hence it is statistically proved that reminiscence therapy is effective in improving self-esteem and mental well-being among senior citizens residing in selected convalescent homes.