The labor supply of taxi drivers is consistent with the existence of intertemporal substitution. My analysis of the stopping behavior of New York City cabdrivers shows that daily income effects are small and that the decision to stop work at a particular point on a given day is primarily related to cumulative daily hours to that point. This is in contrast to the analysis of Camerer et al., who find that the daily wage elasticity of labor supply of New York City cabdrivers is substantially negative, implying large daily income effects. This difference in findings is due to important differences in empirical methods and to problems with the conception and measurement of the daily wage rate used by Camerer et al.