This paper proposes a new method for estimating family labor supply in the presence of taxes. This method accounts for continuous hours choices, measurement error, unobserved heterogeneity in tastes for work, the nonlinear form of the tax code, and fixed costs of work in one comprehensive specification. Estimated on data from the 2001 PSID, the resulting elasticities for married males are consistent with those found elsewhere in the literature but female wage elasticities are substantially smaller than those found in most of the literature. Simulations of recent tax acts predict small effects on the labor supply of married couples. (Contains 8 tables, 4 figures and 48 footnotes.)