The differential reflectivity (ZDR) radar signal contains information on the shape and alignment of ice phase hydrometeors. Under certain circumstances, then, this signal and reflectivity factor can be used to identify the presence of hail particles. Such interpretations require knowledge about the scattering properties of various types and shapes of hydrometeors, including ice, water-coated ice, and graupel. These hydrometeors are examined for their differential scattering properties obtained from computations using the transition (T) matrix method of Waterman and an extension of this theory to two-layered bodies. Differential radar cross sections together with circular depolarization ratios are presented, and several instances of possible hail detection by radar using ZDR signatures are illustrated.