The material study of fragile graphic artworks requires adapted analytical methodologies to extract representative information without resorting to sampling. In this paper, a multimodal approach combining non-invasive techniques was developed to specifically characterize the artistic materials used (paper, pigment/filler and binder) in 3 pastel portraits by the famous French pastellist, Maurice Quentin de La Tour (1704–1788). The combination of elemental analyses using X-ray fluorescence and reflectance spectroscopies covering the entire energy range from 25,000 to 400 cm−1, has provided new insights into the nature and state of conservation of the paper support, as well as the composition and application of the pastel materials. Bridging technical art history, conservation science and analytical chemistry, this research offers a unique perspective on the choice of materials of the renown pastellist, and sheds new light on an artistic technique understudied until now.