Introduction: brief discussion of philosophy and historical development of art conservation. The Treatnient of Edouart Manet's <i>Le Bon Bock: Examination and cleaning of a painting with 11 illustrations. An example of Preventive Maintenance: The Constantine Tapestry Installation; Control of light induced deterioration, description of a simple light monitor to measure the action of ultra-violet light vs. total light radiation. Other Conservation Projects and Their Special Problems: The cleaning of a painting by J. M. W. Turner; con-sultation with independent advisers; deterioration of an early synthetic resin construction by Naum Gabo; photographic revelations on a painting by Joan Miro. Conclusions: Future plans for the Philadelphia Conservation Department. The article is written in nontechnical terms and intended for tlie museum membership.