Developments in the project management field are ongoing. This professional field continuously broadens and becomes profounder. Therefore, IPMA has extended its attention from project management to program management, portfolio management and project support (PMO). This has made manifest the need for a reference model in which the various functions and corresponding competences and the relations between them are presented. Not only for HR managers, but also for project and program managers and PMO heads. In the first edition of this book, attention was given to the regular functions in the project management field, as they are applied in the IPMA 4-level system. With the publication of this second edition, the wish has been realized to make a complete function building for the project management field available. The second edition of this book does justice to PMO professionals’ needs for recognition and appreciation of their added value for projects, programs and portfolios. This is a publication of IPMA-NL.