The advancing tertiarization, knowledge intensification, globalization, and the outsourcing of formerly internal company activities are leading to an increasing significance of knowledge-intensive services. The aim of this book is to present key findings from an empirical study of German knowledge-intensive service providers. The analysis includes not only the characterization of knowledge-intensive services and the importance of productivity for these providers but also the determination of productivity at the company level and the classification of critical success factors in the delivery of services in projects.