The 11th conference on aging and stabilization of polymers was held from May 24 to 26, 1989, in Lucerne (Switzerland). These conferences are held annually in Switzerland. They are organized by the Institute of Materials Science of the State University of New York (New Paltz, USA), Dr. Angelos V. Patsis, a professor of this university, being a permanent chairman of the Organizing Committee. For many years Dr. Peter Klemchuk, Head of the Department of Chemical Additives for Polymers, Research Center, Ciba-Geigy Corp., Ardsley (New York, USA), has been a chairman of the Scientific Program Committee. The Organizing Committee includes well-known scientists: Prof. Norman Billingham (Head of Group, Brighton, University of Sussex, England), Prof. Dietrich Braun (Director of the Polymer Institute, Darmstadt, West Germany), Prof. Jean Marchal (Head of Laboratory, State Research Centre, Paris, France), and Professor David Wiles (Head of Department of National Research Council, Ottawa, Canada).