In this paper some important aspects of institutionalization in old age are studied. Compared with old people living in private households, people living in residential care facilities show some sociostructural particularities which are hints at possible factors related to institutionalization. The following analyses of the factors related to institutionalization in old age result in a conformity of objective and subjective reasons: poor health, lack of social network and bad housing conditions in combination with needs for care are essential factors related to institutionalization. In addition, the question of denominational choice of the residential care facility and the question about migration in old age is examined more closely. With regard to the religious community it is amazing that, in spite of secularization, there are major interdenominational differences. A further analysis of regional mobility suggests some sociostructural differences: women and widowed persons for example do not move over far distances (from the private household to the residential care facility), compared to men and married persons.