Usability is an important aspect of Free-Libre Open Source Software (FLOSS), but barriers exist for usability specialists’ participation in such projects. Organizational boundary literature is interested in the tensions of online communities, including FLOSS communities. While this literature recognizes the importance of managing boundaries in online communities, little empirical research has been conducted on actual gatekeeping tactics project members perform against outsiders’ contributions. Based on several years of engaged research with FLOSS projects, we characterize three gatekeeping tactics in FLOSS projects: non-response, social exclusion, and false acceptance. They all have hindered usability work. We also offer examples of usability specialists and their contributions succeeding in avoiding these gatekeeping tactics in FLOSS projects. This paper provides an important contribution to the boundary management literature through detailed examination of gatekeeping tactics in action, as well as to the Human Computer Interaction literature interested in contributing to FLOSS projects through usability work.