This volume contains the proceedings of the 4th International Conference on Veri?cation, Model Checking, and Abstract Interpretation (VMCAI 2003), held in New York city, January 9–11, 2003. The purpose of VMCAI was to provide a forum for researchers from three communities—Veri?cation, Model Checking, and Abstract Interpretation—that will facilitate interaction, cross-fertilization, and the advance of hybrid methods that combine the three areas. With the g- wingneedforformaltoolstoreasonaboutcomplex,in?nite-state,andembedded systems, such hybrid methods are bound to be of great importance. Topics covered by VMCAI include program veri?cation, static analysis te- niques, model checking, program certi?cation, type systems, abstract domains, debugging techniques, compiler optimization, embedded systems, and formal analysis of security protocols. VMCAI 2003 was the fourth VMCAI meeting. The previous three were held as workshops (Port Je?erson 1997, Pisa 1998, and Venice 2002). It is the success of the last meeting, and the wide response it generated, that made it clear the time had come to make it an annual conference.