TheJahn Teller(JT)effectcontinuesto bea paradigmforstructuralinstabilitiesand dynamicalprocessesinmoleculesandin the condensedphase.While thebasic th- rem, rst published in 1937, had to await experimentalveri cation for 15 years, the intervening years saw rapid development, initially in the theoretical arena, followed increasingly by experimental work on molecules and crystals. The International Jahn Teller Symposiumwas established in the mid-1970s, to foster the exchangeof ideas between researchers in the eld. Among the many important developments in the eld, we mention cooperative phenomena...