Popular social media site Pinterest is known for its strong female user base, something often attributed to the links, images, and ideas available on it. We argue that Pinterest’s popularity with women can also be attributed to a kind of gendering that occurs during the sign-up process. We see the sign-up process as a ‘gender script’ that inscribes specific gender performances into Pinterest itself by ‘pre-scribing’ adherence to a dualistic conception of gender and encouraging users to cooperate rather than to compete with each other, to curate content rather than to create it, and to interact affectively with images rather than with text. These behaviors have connections in the broader public imaginary to traditional performances of femininity, thus the kind of introduction and instruction the new user receives when signing up encourage a perception that Pinterest is for women, a perception that is then materialized in user behaviors. We close by arguing for the sign-up interface as an important site of study in new media scholarship and by discussing the ways in which gender scripts might be resisted.