Introduction. This article outlines the theory of gerotranscendence - a psychosocial theory of ageing developed by Lars Tornstam, a Swedish Sociology professor. Description of the theory. Through his theory of gerotranscendence, Tornstam has introduced a new understanding of ageing, stating that human development is a life-long process that continues into old age and that, when optimized, ends in a new perspective. The theory of gerotranscendence focuses on two phenomena: the old person and the ageing process itself. The theory describes both the experience of growing old and the characteristics of a normal and positive old age. Foundation and empirical base of the theory. The theory is based on both the ideas and theories of others as well as on empirical studies. Relevance of the theory and its application in nursing. The theory of gerotranscendence could provide new key concepts for understanding the developmental process of ageing and the transition into old age. This theory facilitates the possibility of structuring care for older people in addition to guiding it. Because the theory describes development and the meaning of development in older age, it is possible to discuss how care of older people could be structured as well as how staff caring for older people could promote the process of ageing.