This research explores the formation and evolution of entrepreneurial teams (ET) in technologybased new firms during the incubation period in a Technology Business Incubator (TBI). Previous work in the incubation literature has overlooked these important TBI prime-micro processes, the processes related to the formation and evolution of the ET during incubation. Informed by a critical realism perspective, a multiple case study methodology coupled with a longitudinal perspective is adopted to study 12 entrepreneurial teams in the context of a technology incubator, BADIR, in Riyadh, the capital of Saudi Arabia. Data on entrepreneurial team members, incubator advisors, and incubator management was collected through 98 interviews, 8 focus groups, 10 informal discussions, and four non-participant observations, over three rounds of data collection across a twelve-month period from January 2019 to January 2020. This research shows that the ETs in these new firms were unstable, changing entities during the period of incubation and that the TBI was deeply involved with, and intervened significantly in, the entrepreneurial teams. Team formation was characterised by three formation dynamics (the initial creation of the ET; changes in membership; and the emergence of sub-teams). ET evolution, which was towards increased professionalisation, was characterised by three social processes (role allocation; leadership transitions; and team conflict). The entrepreneurial team - incubator relationship evolved overtime, and was characterised by (i) resentment, (ii) independence, (iii) conflict, (iv) co-operation, and (v) sufficiency. This research shows the importance of the incubator as a “multifaceted” context characterised by distinct “knowledge”, “administrative”, “social”, “advisory”, and “mediatory” contexts. Furthermore, the model of incubation adopted in the TBI was shaped by the national context (Saudi Arabia) via national policy goals which emphasised the building of strong entrepreneurial teams in technologybased firms as a priority for TBIs.