Heavy metal fluoride glasses are a recently synthesized class of nonoxide amorphous materials whose molecular structure, morphology, and optical behavior are at variance with the more common and conventional oxide-based glasses. This study will treat two specific classes of fluoride glasses, namely, the fluorozirconates and the fluorohafnates, in which the network formers are ZrF4 and HfF4, respectively, with modifiers being BaF2 and fluorides of rare earths, group III elements, or alkalis. These glasses exhibit high transparency over a frequency range spanning the mid-IR to the near-UV. The primary goal of this study is to focus on the intrinsic Rayleigh scattering of these glasses. The principles of quasi-elastic and inelastic light scattering in glasses will be presented and discussed in great detail. The application of Rayleigh and Brillouin light scattering to various heavy metal fluoride glasses has resulted in valuable information for understanding the possible scattering mechanisms in these glasses. In addition, Brillouin scattering measurements allowed the calculation of the elastic and elasto-optic (Pockels) coefficients of the same fluoride glasses. The full implications that the scattering behavior has on the possible fiber optic waveguide application of heavy metal fluoride glasses will be discussed. The physical significance of the elastic constants and elasto-optic coefficients will also be considered on the basis of existing theoretical models.