This volume contains the proceedings of the thirdInternational Workshop on Computer Aided Verification, CAV'91, held in Aalborg, Denmark, July 1-4, 1991. The objectiveof this series of workshops is to bring together researchersand practitioners interested in the development and use ofmethods, tools and theories for automatic verification of(finite) state systems. The workshop provides a uniqueopportunity for comparing the numerous verification methodsand associated verification tools, and the extent to whichthey may be utilized in application design. The emphasis isnot only on new research results but also on the applicationof existing results to real verification problems. The papers in the volume areorganized into sections onequivalence checking, model checking, applications, toolsfor process algebras, the state explosion problem, symbolicmodel checking, verification and transformation techniques,higher order logic, partial order approaches, hardwareverification, timed specification and verification, andautomata.