Amber no older than Oligo-Miocene, and present dayresin from living resin-producing species, can be characterized by IR absorption spectra of the solid dispersed in KBr pellets. The great similarity of entire IR spectra (625 to 4000 cm.^-1) of ambers separated both geographically and by a time interval of millions of years (Baltic, Eocene; Maryland and at Cedar Lake, Manitoba, Cretaceous) suggests that the spectral character may be determined by the botanical source. Consistent Spectra are obtained from 15 resin samples of <i>Hymenaea courbaril from Mexico, Guatemala, British Guiana, Brazil, Venezuela, and Ecuador. Spectra of <i>Pinus resins are reproducible within some species populations, but display appreciable differences where morphological variations are known to occur. Comparison of amber from the Oligo-Miocene Simojovel formation of Chiapas, Mexico, with the resins of present day resin-producing species in the area indicates that much of the amber is derived from the resin of <i>H. courbaril. The principal differences between the spectra can be correlated with the changes expected from polymerization and from atmos pheric oxidation. None of the other modern resin-producers of Mexico have spectra resembling that of Chiapas amber. The IR spectra of Miocene amber from central Sumatra closely resembleS that of <i>Shorea resin from North Borneo. -- AATA