How does costume design generate a performance? How do these specific costumes perform? What might the agency of costume be? What are the creative tools of the costume designer as the artistic leader? This book presents conclusions and photos from the Costume Agency artistic research project that took place from 2018 – 2023 at the Oslo National Academy of the Arts (KHiO) and in collaboration with The Academy of Performing Arts in Prague (DAMU) and Aalto University, including 80 costume designers, lighting designers, performers, and theorists from 15 countries.