Information systems (IS) projects operationalize and achieve organizational strategy. The reality is that IS project success is challenged by complexity. This research adopts a rich approach and includes a broader array of project complexity and success constructs to establish how project complexity influences the multiple dimensions of project success in IS projects. The target sample was project team members who were actively involved in and had implemented any IS projects across any industry. The research analyzed 612 responses using partial least squares structural equation modelling. The findings revealed three constructs influence IS project complexity which in turn influence three dimensions of IS project success. An empirical model explained that IS project complexity significantly influences IS project process success and deliverable success. Furthermore, IS deliverable project success mediates the relationship between process success and strategic success. The paper provides a novel contribution by establishing the basis for developing an organizational framework where practices, policies, and procedures can be developed for managing IS project complexity. This would assist IS project managers and team members manage project complexity more effectively and realize actual business benefits