Agent-based modeling is a vital technique for studying Complex Adaptive Systems (CAS) as evidenced by the growing body of literature spanning disciplines ranging from Biology to the Social Sciences to Computer Science. This inaugural special issue of Springer Complex Adaptive Systems Modeling (CASM) will publish key papers documenting multidisciplinary methods and applications for agent-based modeling of CAS. Agent-based modeling has become essential for the study of CAS. Many documented techniques and proven applications have emerged. This inaugural Special Issue will help consolidate these diverse ideas in a single volume and also help to introduce CASM to relevant communities.