This book discusses different aspects of group recommender systems, which are systems that help to identify recommendations for groups instead of single users. In this context, the authors present different related techniques and applications. The book includes in-depth summaries of group recommendation algorithms, related industrial applications, different aspects of preference construction and explanations, user interface aspects of group recommender systems, and related psychological aspects that play a crucial role in group decision scenarios. Introduces the concepts of group recommender systems including a discussion of existing industrial applications; Provides an in-depth discussion of algorithms and techniques beyond existing basic group recommendation approaches; Includes a discussion of different aspects of human decision making, explanations, and related psychological models.