The development over the last century of the scientific examination of works of art has changed the way that we evaluate these objects. Employing a range of analytical tools, Hirshhorn conservators seek to identify the materials in modern and contemporary works of art in the permanent collection and the ways in which those materials were used. This research has a two-fold goal. One line of inquiry informs conservation treatments by distinguishing between the artist’s original work and any alterations introduced by later restoration or by the aging process. The other area of research examines the artist’s decision-making processes in related works as revealed by the selection of specific materials and deliberate choices as to how these materials were handled, with the purpose of gaining a fuller appreciation of the context and meaning of the artist’s full body of work. New insights into an artist’s creative process frequently come from comparisons between analytical results along with information given directly or indirectly by the artist and other primary, documentary information.