We study the effects of hydrodynamic interactions on the diffusion of hard spheres in concentrated suspensions. Using a multiple-light-scattering technique that measures the early-time behavior, we find Defr/Do^l -(1.86 ±0.07)0, where 0 is the volume fraction of spheres, Z) e ff is the effective diffusion coefficient, and Do is the free-particle diffusion coefficient. This agrees with the linear 0 term calculated theoretically for short-time self-diffusion. The short-time diffusion coefficient is also found to be continuous across the freezing transition.

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