In this article the researcher would like to discuss theories applicable in the field of Geriatric social work practice and enable the practioners to understand relevant aging theories. Moreover this study will help us to understand how aged people reflect their behavior in their walks of life at various stages. These theories focus on social, psychological, physical and medical conditions of aging and its interconnectedness. They also seek to explain the positive and healthy aspects of aging for the professionals working in geriatrics, social services and policy making. Human ageing may be classified into three main aspects of human development which can be articulated through biological, psychological and social ageing theories to bring out how life moves on in the process of aging. Theories give answers, substantiated by authentication obtained by methodical scientific inquiry. Theoretical perspectives also explain why something happens and helps us to justify actions and also to modify the course of action for effective delivery of services. It is found that there are many theories helps to practice Geriatric social work profession, but the researcher found that following theories were highly applicable to the professional arena such as System theory, Disengagement theory, Activity theory, Gerotranscendence, Age stratification theory Cumulative advantage/disadvantage theory, life course theory, role theory ,continuity theory and Psychosocial development theory.