What do IT project managers consider to be the critical skills necessary for project success, and how have they developed those skills? The aim of this research has been to answer these questions. We interviewed 23 experienced IT project managers from 11 organizations, focusing first on what the managers perceived as their most critical project management skills, and then on how they had developed those skills. We also discussed their exposure to a wide variety of organizational development interventions. By focusing on how project managers actually learned critical skills, we have been able to uncover the importance of informal learning channels, often involving project experiences, for the development of IT project management skills.