This book constitutes the refereed proceedings of the 4th International Conference on Tools and Algorithms for the Construction and Analysis of Systems, TACAS'98, held in conjunction with ETAPS in Lisbon, Portugal, in March/April 1998. The 28 revised full papers presented together with an invited talk were selected from a total of 78 submissions. The volume is devoted to conceptual foundations, development, and applications of tools and algorithms for the specification, verification, analysis, and construction of software and hardware systems. The papers are organized in sections on model checking, design and architecture, various applications, fielded applications, verification of real-time systems, mixed analysis techniques, and case studies and experience.