One major obstacle to requirements engineering (RE) is the growing complexity of today's systems. Such a complexity can only be fficiently by powerful abstraction mechanisms as incarnated by goal-modelling techniques. Unfortunately, the research efforts in this area are fragmented, which is a major impediment to a wide adoption by practitioners. In this work, we describe our approach how to aim the fragmentation by adopting a rigorous and novel approach for comparing and integrating goal modelling languages (GMLs). We investigate both syntax (using the principles for the effective communication) and semantics (using the UEML approach and the ISSRM reference model) and apply GMLs to solve domain specific problems (e.g. for security risk management). We hope to improve the coordination of research in this field, so that a comprehensive, sound, efficient, standard and tool-supported goal modelling language can emerge, be put into the hands of IS developers, and that the overall quali...