This Festschrift honors the remarkable career of Prof. Dr. Dimitris Karagiannis whose research has been focused on metamodeling, method engineering and its application in practice. Metamodeling stands for the design and implementation of modeling languages, conceptual modeling methods and related tools. This book contains fourteen contributions by close collaborators of Dimitris Karagiannis from academia, research, and industry. Each chapter honors the extraordinary inspiration that he provided during remarkable and ongoing collaborations. They cover the topics of conceptual modeling, semantic engineering, business process management, ontologies, enterprise architecture and knowledge management. They not only refer to research results, but also to tools like the ADOxx metamodeling platform for implementing domain-specific modelling tools and educational efforts like the Open Models Initiative Laboratory, aka OMiLAB, or the NEMO Summer School on conceptual modeling.  The contributions by authors with ample experience in metamodeling reflect on the state of the field and possible applications and trajectories to the future. They are compiled in honor of Dimitris Karagiannis and his outstanding work in this domain.