This exploratory case study analyzed the reported learning experiences among the multidisciplinary practitioners employed in the development of edX courses for a pioneering MOOC program targeted at Latin America and Caribbean. It applied work-based learning theory and activity theory to answer the question of whether and how a group of 20 participants--including subject matter experts, instructional designers, administrative assistants, platform technicians, and media producers--experienced work-based learning through their collaboration during the MOOC program's initial professionalization period. Using qualitative research methods via interviews, observation, and document analysis, it illuminated the practical, pedagogical, and organizational factors that participants identified as critical for succeeding in their jobs. The principal study finding indicated that the entirety of participants experienced work-based learning in response to systemic tensions related to one or more of the five phases of the MOOC design cycle. The secondary findings concluded that participants encountered significant pressures and opportunities for learning as a result of: developing educational resources or learning activities (80%), the need for improving organizational processes (85%), and facing constant technological upgrades (75%). Finally, the study recommends that MOOC design teams: (1) rethink the role of the instructor vis-à-vis the techno-pedagogical affordances of the MOOC platform; and (2) design adaptive organizational structures that support a plurality of sociomaterial workflows.