A study is made of the free vibrations of sandwich beams with viscoelastic cores. The study includes formulation of the equations of motion and natural boundary conditions, derivation of expressions for the modal distribution of damping based upon small damping assumptions, numerical examples and a supporting test program. Significant among the numerical results were the high damping rates calculated for beams with steel facings and butyl rubber cores. It was found, however, that the calculated and test values were not in accord. This lack of agreement signifies the necessity for greater refinement in both analytical methods and test procedures.