The “China Girl” has appeared in more films than any actress, but she is almost never seen. Used in industrial film laboratories since the late 1920s, this image-nearly always a woman positioned next to color swatches and patches of white, gray, and black—is clipped to the leader of a film reel and used throughout the processing, developing, and printing of photochemical film to determine the desired exposure, density, and ideal appearance of the human body. This article addresses the China Girl's essential but often overlooked role in film history, specifically as it pertains to questions of race, gender, and visibility. It also surveys the work of various experimental filmmakers, including Owen Land, Morgan Fisher, Barbara Hammer, Sandra Gibson and Luis Recoder, Cécile Fontaine, and Mark Toscano, who have used the China Girl image to explore issues of celluloid materiality, the behind-the-scenes workings of the film industry, and the often marginal role of women both in front of and behind the camera.