This book constitutes the refereed proceedings of the workshops co-located with the 18th International Conference on Practical Applications of Agents and Multi-Agent Systems, PAAMS 2020, held in L’Aquila, Italy, in October 2020. The total of 21 full and 13 short papers presented in this volume were carefully reviewed and selected from 57 submissions. The papers in this volume stem from the following meetings: Workshop on Agent-Based Artificial Markets Computational Economics (ABAM); Workshop on Agents and Edge-AI (AgEdAI); Workshop on Character Computing (C2); Workshop on MAS for Complex Networks and Social Computation (CNSC); Workshop on Decision Support, Recommendation, and Persuasion in Artificial Intelligence (DeRePAI); Workshop on Multi-Agent Systems and Simulation (MAS&S); Workshop on Multi-agent based Applications for Energy Markets, Smart Grids and Sustainable Energy Systems (MASGES); Workshop on Smart Cities and Intelligent Agents (SCIA).