Rene Magritte (1898-1967) is the most famous Belgian artist of the twentieth century and a celebrated representative of the Surrealist movement. Much has been written about his practices, artistic community, and significance within the history of modernism, but little has been documented regarding his process. Though he was reluctant to discuss his techniques and materials, practical concerns over media and cost shaped his output and legacy. This volume examines fifty oil paintings made by Magritte between 1921 and 1967, now held at the Royal Museums of Fine Arts of Belgium. This technical study of his works using noninvasive scientific imaging and chemical analysis reveals the artist's painting materials, his habit of overpainting previous compositions, and the origins and mechanisms of surface and pigment degradation. Of interest to conservators, scientists, curators, and enthusiasts of twentieth-century art, this book expands our understanding of Magritte the artist and provides new and useful findings that will inform strategies for the future care of his works.