A participant-observation study of a visiting pet therapy program for the residents of three geriatric facilities has revealed several unintended social effects. Though the program is designed to operate in a similar way in all three institutions, its impact varies with the size of the facility, the health status of the residents, and the format that visits follow in each home. These differences yield distinct levels of privacy, interpersonal sharing, and human/animal contact. The presence of pets and the people who accompany them also trigger distinct reminiscing patterns pertaining to childhood and pet loss. In addition, some elderly residents participate mainly to relate to humans rather than animals. Furthermore, certain patients perceive pets as sources of moral value: they use their presence to assess human qualities and their own treatment by others. Program volunteers also develop on-going, intense bonds with residents whose emotional demands they sometimes find it difficult to meet.