Using Jean-Jacques Rousseau’s scène lyrique Pygmalion (1762/1770) as its case study, this chapter delves into the complexities of eighteenth-century stage costume and its recreation today, specifically with a view to historically informed performance in historical spaces. It presents the tools for a ‘historically informed costume’ methodology, which requires us to take visual, textual, and material sources, anecdotal evidence, aesthetical treatises, memoirs, and reviews into account. These materials offer insights into the physical as well as the visual properties of costume, its meaning, and its agency on stage.