An introduction to a forthcoming volume, Female Labor Supply: Theory and Estimation. This book will contain seven essays by members of the Labor and Population Program at The Rand Corporation. These essays deal with a variety of theoretical and statistical issues confronted in the estimation of labor supply functions. In addition to the problems encountered with censored samples in estimating wage and hours functions, the topics include the choice between linear and non-linear methods of estimation, the availability of alternative definitions of labor supply (participation, weeks worked, and annual hours), the role of time and money costs in the decisions to work and the extent of work, and the ability of the life-cycle approach to interpret otherwise anomalous empirical estimates. In each paper, theoretical models are tested empirically using a variety of existing micro-data sets.