The 12th conference on aging and stabilization of polymers was held from May 21 to 23, 1990, in Luzern (Switzerland). As before, the conference was organized by the Institute of Materials Science, the State University of New York (New Paltz, USA) being a permanent chairman of the organizing committee. For many years Dr. Peter Klemchuk, Head of the Department of Chemical Additives for Polymer Research Center, Ciba-Geigy Corp., Ardsley (New York) has been a chairman of the scientific program committee.