From the black peasant uniforms of the Khmer Rouge to the clothes worn by prisoners entering the S-21 prison, textiles have been an overlooked aspect of Cambodia’s material culture of the late 1970s. At the Tuol Sleng Genocide Museum (TSGM), textile fragments, garments, and other objects had been abandoned for decades. In 2017, with the support from the US Embassy Ambassadors Fund for Cultural Preservation, American textile conservator Julia Brennan devised a unique mass-treatment protocol and training specific to both the climate and the nature of genocide artifacts, working with the in-house conservation team. Approximately 3,000 pieces of clothing were inventoried, photographed, conserved, and stored in a climate-controlled system. Combining a historical and material perspective, this chapter describes how Khmer Rouge politics redefined the clothing worn by Cambodians in the 1970s and how the TSGM’s collection reflects those political effects. It outlines the specific challenges of preserving this archive in terms of ethics, protocol, and training. Finally, it examines how defining this collection as a ‘textile archive’ brings this realm of materials in immediate dialogue with the TSGM paper and photographic archive, to inform the individual and collective stories of S.21’s victims.