One Week | One Tool was a twice-funded NEH Institute for Advanced Technology in the Humanities, bringing together a diverse group of academic and information professionals to conceive and build an open-source software tool in one week in a digital humanities “barn raising.” First hosted in the summer of 2010 and again in the summer of 2013, One Week | One Tool brought twelve digital humanists of diverse disciplinary backgrounds and practical experience to build a working piece of scholarly software. A short course of training in principles of open-source software development was followed by an intense six days of doing and a year of continued remote engagement, development, testing, dissemination, and evaluation. Comprising designers and developers as well as scholars, teachers, project managers, outreach specialists, and other non-technical participants, the group conceived a tool, outlined a roadmap, developed and disseminated an initial prototype, laid the groundwork for building an open-source community, and made first steps toward securing the project’s long-term sustainability. The 2010 team launched Anthologize, a WordPress plugin for reformatting a blog as a book. The 2013 team launched Serendip-o-matic, a search engine using topic modelling to match an author’s text to items pulled from the DPLA, Europeana, Trove, and other open-access archival collections.