The constrained-layer damping mechanisms on plates, beams, and tubular structures have been experimentally studied with well characterized viscoelastic materials. The Kerwin analysis [1] on plate damping has been extensively verified; important variables can now be individually controlled to achieve optimum performance. The validity of extending the plate theory to box-beams has been established; certain preferred cross-sectional geometries for highly damped beams are now defined. Experimental evidence has shown that concentric treatments are ineffective to dampen bending vibrations of tubular structures. Analyses of the strength of laminated composites have shown that structural integrity can be retained. Equations have been derived to predict the static and dynamic rigidities of such laminates.