Photon Density Wave (PDW) spectroscopy is applied for characterizing the scattering properties, i.e. the reduced scattering coefficient μs′, of highly concentrated mono- and bidisperse polymer latices. The theory for dependent scattering is reviewed and analytical expressions for the structure factors for hard sphere interaction in mono- (HSPYA) and bidisperse (BHSPYA) systems are given. From the scattering properties particle sizes of mono- and bidisperse polystyrene latices are determined as well as the relative amount of small and large particles for the bidisperse case.