The method of Zhang et al. (2001) is used to retrieve the governing parameters of constrained gamma drop-size distribitions (DSDs). The method utilizes polarimetric radar measurements of radar reflectivity and differential reflectivity and an empirical relation found between the shape and slope parameters of the distribution. A comparison of radar-retrieved DSD parameters and disdrometer observations show that trends and magnitudes of the total drop concentration, drop median volume diameter, distribution shape, and distribution slope are generally well matched. The method is then applied to a convective-stratiform rain event to study the evolution of the DSD.