Preference Modeling for Group Decision and Negotiations.- Solving Multicriteria Group Decision-making (MCGDM) Problems based on Ranking with Partial Information.- How to Address Multiple Sources of Influence in Group Decision-making.- From a Nonordering to an Ordering Approach.- Choosing a Committee under Majority Voting.- Reciprocity and Rule Preferences of a Rotating Savings and Credit  Association (ROSCA) in China: Evolutionary Simulation in Imitation Games.- Modeling the Conflict within Group Decision Making: A Comparison Between Methods that Require and do not Require the Use of Preference Aggregation Techniques.- Collaborative Decision Making Processes.- UX challenges in GDSS: An Experience Report.- A Voting Procedures Recommender System for Decision-making.- Why is it Worth it to Expand your Set of Objectives? Impacts from Behavioral Decision Analysis in Action.- Identifying and Ranking Critical Success Factors for Implementing Financial Education in Taiwan Elementary Schools.- Conflict Resolution.- War as a Technique of International Conflict Resolution –  an Analytical Approach.- The Effect of Conformists’ Behavior on Cooperation in the Spatial Public Goods Game.- Effect of Pollution on Transboundary River Water Trade.- Behavioral OR.- Cognitive Style and the Expectations Towards the Preference  Representation in Decision Support Systems.- Cue Usage Characteristics of Angry Negotiators in Distributive Electronic Negotiation.- Opinion Dynamics Theory Considering Trust and Suspicion in  Human Relation.- Negotiation Support Systems and Studies (NS3).- A Framework for Gamified Electronic Negotiation Training.- Application of Data Mining Methods for Pattern Recognition in Negotiation Support Systems.

This book constitutes the refereed proceedings of the 19th International Conference on Group Decision and Negotiation, GDN 2019, held in Loughborough, UK, in June 2019. The field of Group Decision and Negotiation focuses on decision processes with at least two participants and a common goal but conflicting individual goals. Research areas of Group Decision and Negotiation include electronic negotiations, experiments, the role of emotions in group decision and negotiations, preference elicitation and decision support for group decisions and negotiations, and conflict resolution principles.The 17 full papers presented in this volume were carefully reviewed and selected from 98 submissions. They were organized in topical sections named: preference modeling for group decision and negotiations; collaborative decision making processes; conflict resolution; behavioral OR, and negotiation support systems and studies.