This book constitutes the revised selected papers from the 14th European Conference on Multi-Agent Systems, EUMAS 2016, and the Fourth International Conference on Agreement Technologies, AT 2016, held in Valencia, Spain, in December 2016. The 43 papers and 2 invited papers presented in this volume were carefully reviewed and selected from 68 submissions. The papers cover thematic areas as agent and multi-agent system models, algorithms, applications, simulations, theoretical studies, and for AT the thematic areas are: algorithms