In the 20th century, houseparent families represented a significant resource in the long-term care of people with mental illnesses and physical disabilities in diaconical care settings in Germany. In theory, such families could therefore be understood as a type of institutional family: groups which occasionally use familial patterns of reciprocity but are not themselves families. As little empirical material on life in institutional families existed, a qualitative study was undertaken to explore the experiences of contemporary witnesses, particularly those who had experienced the duties and responsibilities of housemothers in the second half of the 20th century. This paper has combined the experiences of residents (n= 8) and biological children of houseparents (n= 5) from a qualitative study (n= 42). The qualitative study took a grounded theory approach, with the phenomena of power and domination forming the central category. The findings show that life in houseparent families of the time was shaped by rules which the family members had to obey. This study explores a highly controversial area which is of great relevance for current mental health nursing practice: the power relations in diaconal families. This demonstrates the importance of integrating autonomy and empowerment into everyday communal life and contributes to professional nursing practice.