(A division of labor model was applied in a study of the efforts to minimize health crises and maximize benefits of medical protocols in eight families, each with a hemophilic school-age boy. Subject families were studied for a 5-year period through participant-observer techniques including interviews with the children in their homes, with the mothers, most of the fathers, several of the siblings, school teachers, and health care providers. Analysis of interview transcripts and process notes on observations found two distinctive but linked categories related to division of labor: (1) who in the family becomes central in decision-making and responsible for the home-based medical work; and (2) when (in the children's development) shifts in management occur. Interview excerpts and discussion are organized into the following section titles: "Becoming Medical Technologists at Home"; "Becoming Peer Group Members Away from Home"; and "Siblings' Work--Further and Concurrent Divisions of Labor." Noted in the summary are such differences between parents and children as the importance of protection from physical injury (for the parents) and the importance of peer group relationships (for the children). (DB)