Research in the area of abstract data types started about 20 years ago. Since then there has been continuous activity with strong influence both on the applications and the theoretical foundations of methodologies for software design. This volume contains the proceedings of the 9th Workshop on Specification of Abstract Data Types, held jointly with the 4th COMPASS Workshop in Spain in 1992. The main topics covered were: object-oriented specifications, rewriting methods, specification languages and associated tools, type systems, and the algebraic specification of concurrency.