[영문]This paper uses the qqqquot;adult goodsqqqquot; method to estimate the full costs of children. Full costs include both expenditure and time costs. Adult personal time (comprising pure leisure, sleep and other personal care) is used as the adult good. Previous research has shown that the presence of children in the household leads to a reduction in adult personal time. This paper develops a simple economic model of the household to show how this information can be used to develop an equivalence scale for adult consumption that takes account of both the expenditure and time costs of children. Preliminary estimates using Australian data suggest a very large cost?much higher than that typically assumed for expenditure costs. The full cost of children declines with age, despite the expenditure cost rising. The paper discusses the limitations of the adult good method and the assumptions needed to draw welfare conclusions from these and other estimates of child costs.