The increasing use of projects and programs by organizations to achieve business strategy and goals has led to the need for understanding project portfolio management. Along with the increasing diffusion of portfolio management, a new managerial role has evolved: the portfolio manager. This new role is pivotal in planning and controlling complex project landscapes more effectively and efficiently. This study investigates the governance structures and the roles, responsibilities, and practices of portfolio managers. A sequential mixed-method approach under a realism paradigm is used. This article presents the first-stage qualitative study, using an inductive interview-based approach with six portfolio managers from six organizations in Australia. The results of six case studies from the qualitative study are used to validate the research model developed based on previous research. It developed the constructs for the concept of portfolio context and the roles, responsibilities, and practices of portfolio managers.