The algebraic specification of abstract data types is now a well establishedresearch topic in computer science. This area influences both applications and theoretical foundations of methodologies which support the design and formal development of reliable software. The Seventh Workshop on Specification of Abstract Data Types took place in Wusterhausen/Dosse, April17-20, 1990, and was organized in cooperation with the ESPRIT Basic Research Working Group COMPASS. The main topics covered by the workshop were: - Modularization - Object orientation - Higher-order types anddependent types - Inductive completion - Algebraic high-level nets.