Britain along with other western European countries has seen a marked decrease in allegiance to traditional forms of Christianity during the latter part of the 20th century. Although church attendance remains relatively high among older people compared with younger age groups, there has been little or no investigation into the stability or change of people's religious belief and practice with increasing age. This paper present findings on these issues from the Southampton Ageing Project, which from 1977–78 to 2002 followed 342 people almost all of whom had had an entirely Christian religious education and all of whom at the outset were aged 65 or more years. Although religion has continued to have considerable meaning in the lives of up to one-half of the participants, approximately one-quarter of the sample expressed a declining commitment to a religious faith and to church membership. The participants' accounts of their recent life experiences, for example following bereavement, give instances of disappointment with the support that they received from institutional religion and show that this was a factor in their declining adherence. They also provide suggestions for further investigation into the origin of this decline. The conclusion argues that the study of older people's religious and spiritual beliefs and practice should be integrated with the investigation of self and identity and of sources of existential meaning in later life.