A dynamic model of labor supply under uncertainty with endogenous human capital accumulation is developed and estimated using 1968-81 Panel Study of Income Dynamics male panel data. Given a learning-by-doing technology for human capital investment and a translog utility function, structural parameters for preferences and technology are estimated from the orthogonality conditions implied by the Euler equations assuming rational expectations. The parameter estimates conform to economic theory. Simulations of the model suggest that the intertemporal labor supply elasticity with endogenous wages will rise over the lifecycle, producing different policy implications than typical models with exogenous wages and constant intertemporal elasticities. Copyright 1989 by Economics Department of the University of Pennsylvania and the Osaka University Institute of Social and Economic Research Association.