Damping systems based on interpenetrating polymer networks (IPN's) provide noise and vibration attenuation over broad temperature and frequency ranges. Semicompatible latex IPN's are employed in both extensional and constrained layer configurations. The damping behavior of IPN's of compositions poly(ethyl methacrylate)/poly(n-butyl acrylate) [PEMA/PnBA], poly(ethyl methacrylate–co–ethyl acrylate)/poly(n-butyl acrylate–co–ethyl acrylate) [P(EMA–co–EA)/P(nBA–co–EA)], and poly(vinyl chloride)/poly(butadiene–co–acrylonitrile) [PVC/P(B–co–AN)] were investigated and compared to both commercially available materials and to theory. The damping of both the PEMA/PnBA and the P(EMA–co–EA)/P(nBA–co–EA) IPN's in a constrained layer configuration was significantly better, over a broad temperature range of −10° to 60°C, than the commercial materials. In addition, the P(EMA–co–EA)/P(nBA–co–EA) IPN was found to be effective in damping phenolic-impregnated Kevlar cloth laminates. A reduction of 10 dB in impact noise resulted with a 6–8% by weight layer inserted between the Kevlar-phenolic panels. The relationship between the peak damping temperature of a constrained layer system to maximum tan δ along with that of an extensional damping system to maximum E″ was also demonstrated. Although the amount of damping predicted by the theory approached that found experimentally, sufficient differences existed such that the exact detail of the damping curve was not described.