4.2 "Comments on 'Estimation of a Stochastic Model of Reproduction: An Econometric Approach'" James Heckman and Robert Willis have embarked on a program of research that extends economic rationality to the bedroom and promises to make them the Masters and Johnson of economics. Their paper contains some ingenious ideas for modeling and estimation; ideas that are potentially useful in other areas of economics where discrete choices or outcomes occur. On the other hand, the authors' empirical results are not an unmixed success, and fail to establish that the technology of childbearing is a fertile area for application of the theory of rational behavior. The lack of significance of economic factors in explaining fecundability suggests that this paper may be approaching the outer limits of the universe of the new home economics. My discussion will be divided into three parts. First, I shall comment on the modeling of the childbearing technology. Second, I shall make a few observations on the statistical methods developed in the paper. Third, I shall comment on the empirical results.