This book constitutes the thoroughly refereed post-proceedings of the Forth International Workshop on Environment for Multiagent Systems, E4MAS 2014 10 years later, held in Paris, France, in May 2014 as an associated event of AAMAS 2014, the 13th Conference on Autonomous Agents and Multiagent Systems. The 15 revised papers presented were carefully reviewed and selected from numerous submissions. The papers are organized in topical sections on connecting agents, environments, and humans, environments for complex systems, virtual and simulated environments, open agent environments and...