Phase speeds of both upwind and downwind traveling, wind-generated waves 4.1, 9.8, 16.5 and 36 cm in wavelength were measured by using microwave Doppler spectrometry. Advective effects of the wind drift could be separated from inertial pressure effects by taking sums and difference of the phase speeds of upwind and downwind directed waves. Boundary layer parameters inferred by fitting measured phase speeds to those predicted by first-order perturbation of the interfacial, flow are in general agreement with parameters derived from other measurements. Attempts to refine the interpretation by using available theories of phase speeds of finite amplitude, irrotational waves degraded the agreement; in fact, the measured fetch dependence of phase speeds was opposite that predicted by these theories.