With the increasing focus on organizational learning in project organizations, it becomes curtail to understand the learning process and how it evolves within project teams. There is limited and shallow coverage of learning and its challenges in a project team environment. Moreover, there is contradicting views in the literature as to whether learning is truly happening on projects. This paper will investigate through multiple case study approach project team learning in mega projects. Key findings from this study will identify the root causes of project team failure to learn and the challenges and barriers faced by project teams in fostering a learning culture. Moreover, the study will highlight a set of enablers that can be implemented in projects to enhance the learning capabilities of both individuals and groups working as project teams which will eventually lead to a learning organization.