All too often polymer composite materials, commonly called plastic, are described solely by the base polymer. However, material properties also are tied to plasticizers and other components. Thus, accurate characterization of plastic requires multi-component search strategies. This is especially critical in the museum context, where the challenge often is to identify and diagnose collections of deteriorating artifacts of unknown composition that span two centuries of evolving technology. Raman spectroscopy is a potentially non-destructive tool that can distinguish the constituent compounds, but relies on comprehensive spectral libraries and innovative approaches to decipher, and in effect reverse engineer, mixtures. In response to this need, 100 polymer and 90 plasticizer reference materials were analyzed using Fourier transform and dispersive Raman spectroscopy. These spectra form the basis of a searchable reference library of 19th-21st century materials. In keeping with the Smithsonian mission to increase and diffuse knowledge, these spectra will be made freely downloadable on the Smithsonian Institution website (www.si.edu).