We have been able to analyze the autocorrelation function of the light scattered from the rabbit lensin vivoin terms of a two component, exponential fit. We have measured the intensity and the decay rate associated with each of these two components as a function of age and position in the lens. As far as is possible we have interpreted these results in terms of molecular changes in the state of association of the protein constituents in the aging rabbit lens. These studies suggest that the method of quasielastic light scattering spectroscopy can provide a useful probe of the protein modifications that occur in both normal and cataractous human lenses.