This book constitutes the refereed proceedings of the 4th International Conference on Verification, Model Checking, and Abstract Interpretation, VMCAI 2003, held in New York, NY, USA in January 2003. The 20 revised full papers presented together with five invited contributions were carefully reviewed and selected from 43 submissions. The papers are organized in topical sections on static analysis, dynamic systems, abstract interpretation, model checking, security protocols, and formal methods.