We are proud to celebrate the 50th anniversary of the calixarenes. In 1944, Zinke and Ziegler proposed a cyclotetrameric structure for an oligomer extracted from the condensation product mixture obtained by reacting p-tert- butyl phenol with formaldehyde in the presence of sodium hydroxide. Fifty years on, calixarenes are the basis of many different areas of chemical research, with development occurring at an increasing pace over the past decade in particular. The present volume does not provide an overview of all these developments, but is rather a celebration of some of the highlights. This presentation of the intricate mosaic of diversity that characterizes calixarene chemistry will stimulate