Many IT projects fail due to the lack of collective competence; however, collective competence development in IT project programs and portfolios has received limited attention. Obviously, the actors involving in project programs and portfolios are interdependent and form an IT- project ecosystem, and our study views these actors as critical resources of IT projects. Thus, resource orchestration is a sound guiding theory that we adopt to examine the dynamics of collective competence development in the IT-project ecosystem. We construct a theoretical framework aligning the orchestration strategy with the ecosystem structure, and guided by this framework, we conduct an in-depth case study. This study reveals a process model towards collective competence development, which consists of structuring, bundling, and leveraging phases. Our findings contribute to the existing literature of IT project management, competence management, and resource orchestration. Organisations can use this model step- by-step to develop collective competence at the ecosystem level.