This paper describes the historical development of conservation in the Western world, and how the philosophical approach to conservation has evolved through time. In the past, conservation/restoration has been very different from what it is today, and the profession has evolved slowly. Until the work of art was respected as an historical document, repainting and alteration was common and accepted. The aim of restoration was not to preserve the original work of art; the emphasis was on renewing or improving the work. With the beginning of the large public collections in the 18th century, restoration activity increased and became better organized. Restoration ws undertaken by restorers, rather than artists, but it was the treatment itself that was important, not the actual needs of the painting. Conservation in the 20th century has been marked by change and development. This paper discusses the growth of in-house conservation, the development of an international network of conservators, the influence of the scientist on the examination and treatment of objects, and most important, the development of a guiding philosophy, that have brought us to conservation as we know it today. Conservation today is governed by a responsibility to the historic and aesthetic integrity of the object. The main activities of conservators today are: preventive conservation and training, examination, restoration treatment, and research. The paper describes how conservation of our collections has become a shared responsibility, involving communication and co-operation among the conservator and the curator, the artist, and the conservation scientist.