Quasi-elastic light scattering spectroscopy was used to measure the mutual diffusion coefficient D-m of Triton X-100 micelles, and the probe diffusion coefficient D-p of polystyrene latex spheres diffusing through micelle solutions. The solution ionic strength has a substantial effect on aggregation number N and hydration delta of Triton X-100 micelles, N and delta both increasing with increasing salt concentration. This behavior may be qualitatively described as arising from a salt-induced change in the location of the water/Triton X-100 cloud curve.