From the Preface: The Proceedings contain papers presented at the 1st Working Conference on "Reliability and Optimization of Structural Systems", Aalborg, Denmark, May 6-8, 1987. The conference was the first scientific meeting of the new IFIP Working Group 7.5 on "Reliability and Optimization of Structural Systems". The purpose of the Working Group 7.5 is: - to promote modern structural system optimization and reliability theory, - to advance international cooperation in the field of structural system optimization and reliability theory, - to stimulate research, development and application of structural system optimization and reliability theory, - to further the dissemination and exchange of information on reliability and optimization of structural system optimization and reliability theory, - to encourage education in structural system optimization and reliability theory.