Bullard, Julia2023-03-172023-03-172016https://dl.eusset.eu/handle/20.500.12015/4455Contributions from the crowd are not just content-sustainable systems require ongoing behind-the-scenes infrastructural work. In this paper, I explore potential strategies for motivating volunteer contributions to large-scale collaborative projects when volunteer contributions are procedural in nature and largely invisible in the published project. I use a user-driven classification system for a large, established, and growing fanfiction collection as an example of a successful project of this type. I compare the challenges and possibilities to those established in the study of open source, wiki, and citizen science projects, which share with classification design a need for distributed human contributions to procedural tasks. Textual analysis of recruiting and training documents, informed by prolonged engagement in the community, reveals strategies that diverge from other HCI research on motivation, such as a focus on work rather than fun and insider rather than public recognition.enuser contributionsinvisible workclassification systemsmotivating volunteersharry potter spoilerText/Conference Paper10.1145/2957276.2957295