A comprehensive pediatric care program was offered to a sample of urban poor families, with special attention being paid those families who had indicated that they would be "hard to reach" or who had a specific social problem. The majority of families approached readily accepted this offer of medical care. With considerable further effort 75% of the hard-to-reach families could be brought into the program. The presence of a specific social problem, illegitimacy, while not precluding a family's being enrolled, did decrease participation and require more effort. Residential mobility and family disorganization were the major handicaps encountered. Race, mother's education, and children's age also influenced the outcome. These efforts, while rewarding, entailed considerable time and expense; whether this is worthwhile depends on the demonstration of actual benefits of comprehensive care to the families.