This paper is concerned with the development of a general model for predicting material damping in laminates based on the strain energy method. In this model, the effect of interlaminar stress on damping is taken into accounts along with those of in-plane extension/compression and in-plane shear. The model was verified by carrying out the damping measurements on $90^0$ unidirectional composite beams varying length and thickness. The analytical predictions were favorably compared with the experimental data. The transverse shear($$sigma$_{yz}$</TEX>) appears to have a considerable influence on the damping behaviors in $90^0$ unidirectional polymer composites. However, the other interlaminar stresses($$sigma$_{xz}$</TEX>, $$sigma$_z$</TEX>) were shown to have little impact on vibration damping in $90^0$ laminated composite beam.