the book constitutes the refereed proceedings of the 6th international conference on verification, model checking, and abstract interpretation, vmcai 2005, held in paris, france in january 2005. the 27 revised full papers presented together with an invited paper were carefully reviewed and selected from 92 submissions. the papers are organized in topical sections on numerical abstraction, verification, heap and shape analysis, abstract model checking, model checking, applied abstract interpretation, and bounded model checking.