An examination was made of the internal boundaries of families in treatment for father-daughter incest and families in treatment for other concerns. Family boundaries are described as the internal rules that define when and how family members participate within the family. Information was gathered through the use of individual in depth interviews with mothers and daughters from both groups of clinical families. A descriptive narrative about family boundaries was developed using the core category of family rules, with subsidiary categories that included family organization and family communication. Three major themes of awareness, control, and consistency emerged from the data as clinically useful concepts for describing perceptions of family rules. One important finding was that mothers and daughters from both clinical groups were found to be similar in their perceptions of family rules. A major difference between the groups related to marital power and control, with mothers in the incest treatment group reporting less control over family rules prior to the disclosure of abuse and the initiation of treatment than mothers in the control treatment group. The results of the research suggest therapists should avoid stereotyping families who are in treatment for father-daughter incest and focus instead on assessing the unique factors that contribute to a family's vulnerability to incest. The importance of providing emotional and social support for individual family members following the disclosure of father-daughter sexual abuse is also highlighted. / Ph. D.