The high complexity and diversity of today's design projects demands the participation of multiple experts. The participating experts can influence the design process by sharing their perspective, expertise and resources. The involvement of various experts is often known as collaborative modeling and design. A collaborative modeling environment can encompass various geographical or organizational boundaries. In this paper, we provide a classification to study various aspects of this important issue through the exploration of the existing models, methods and applications in this area. The paper further addresses both modeloriented and artifact-neutral collaboration approaches and enumerates their features. The paper introduces the features of and classifies several relevant applications. The classification can serve as a guideline for customizing a suitable setting for a collaborative modeling process based on given requirements, needs and demands. Several suggestions for future work are also provided.