The papers collected in this volume represent the formal proceedings of the Third European Symposium on Calcified Tissues which was held in Davos, Switzerland from 11th to 16th April 1965 under the sponsorship of the Laboratorium fur experi­ mentelle Chirurgie, Schweizerisches Forschungsinstitut Davos. This Symposium fol­ lowed the now established tradition of the previous Symposia held in Oxford in 1963 and in Liege in 1964. Participation was again strictly on a residential basis. This year the Schatz alp Hotel provided a scenic and secluded meeting place high on a mountain side overlooking Davos yet close to the Forschungsinstitut in which the opening session of the Symposium was held. The papers and communications published in the volume are arranged in order of presentation and are grouped under the five main themes selected for discussion by the Symposium, namely, "Cell function in the formation, maintenance and destruc­ tion of osseous tissue", "Response of calcified tissues to mechanical factors", "Mecha­ nisms of mineralization and diseases related to mineral deposition", "Hormones and bone" and "Fundamental structure of dental hard tissues". The programme consisted of a number of review lectures given by invited speakers and of short communications in relation to each of the above themes. No attempt was made to record the dis­ cussions to the papers as, being a residential meeting, the more valuable and interesting interchanges took place informally in small discussion groups and not within the time schedule of the prearranged programme.