This paper presents a methodology for estimating the full cost of parental time allocated to child-care activities at home. Building upon the human capital hypothesis, a model is developed in which the cost of an hour diverted from labor market activity is seen as consisting of three components: 1) direct wages foregone; 2) investments in on-the-job training foregone; and, 3) human capital losses associated with skill depreciation. The model is estimated for a sample of 535 mothers of elementary school children in an affluent district in New York State. For this sample, the full cost of an hour spent in child-care activities is estimated to be approximately twice the observed market wage. In terms of total resources entering the educational process (school plus home inputs), the analysis suggests that small changes in out-of-school time use represent substantial changes in the overall length of educational resources allocated to children. (Author)