New occupations are emerging that have high job demand in the market, but lack a coherent body of disciplinary knowledge. For example, user experience (UX) design is an emerging occupation that has not been adequately supported by the traditional educational system. For learners beginning their undergraduate education, there is no concrete path to follow to become a UX professional, due to few UX-focused undergraduate academic programs. Online communities of practices have been recognized as important learning venues, even while institutions of formal education often lag behind in structuring knowledge production and distribution. However, little is known about how knowledge is generated and diffused in online communities in the context of emerging occupations with volatile knowledge boundaries. In this paper, we analyze knowledge production in relation to social roles in an online UX community. We show that knowledge production is highly distributed, involving the participation of community members of varied levels of experience. We discuss how online communities support the development of the UX occupation.