CT This paper presents results from a study examining perceptions and practices of usability in the free/open source software (FOSS) community. 27 individuals associated with 11 different FOSS projects were interviewed to understand how they think about, act on, and are motivated to address usability issues. Our results indicate that FOSS project members possess rather sophisticated notions of software usability, which collectively mirror definitions commonly found in HCI textbooks. Our study also uncovered a wide range of practices that ultimately work to improve software usability. Importantly, these activities are typically based on close, direct relationships between developers and their core users, a group of users who closely follow the project and provide high quality, respected feedback. These relationships, along with positive feedback from other users, generate social rewards that ultimately serve as the primary motivations for attending to usability issues on a day-to-day ba...