The overall objective of our proposed research is to (a) further the understanding of the behavioral mechanisms by which families maintain the health of their children and (b) describe their patterns of utilization and experiences in medical care markets directed to this purpose. We stress the medical element in the family decision-making process for the development of child health. We develop a framework which describes the family's utilization of medical services as a behavioral response to the perceived health status of the child and use it to formulate and empirically test hypotheses concerning such behavior. Integrated within our framework are the sociological, demographic, and economic forces which, individually, have been shown to influence both health status and the use of medical services. The frame-work is operationalized as a series of structural equations, some of which are simultaneously determined. We employ multiple regression techniques and maximum likelihood logit analysis to estimate the parameters of the model. The primary source of data is the Mindlin-Densen (M-D) study, Medical Care of Infants and Preschool Children, a longitudinal and cross-sectional survey covering twenty-one months in the period 1965-66. Geographically, the M-D study encompassed two contiguous health districts in N.Y.C., which were significantly different in socio-economic and health characteristics. One was an urban slum, biracial and ethnically mixed; the other was a bulwark of the white middle class.