This volume contains the proceedings of ICALP 90, the International Colloquium on Automata, Languages and Programming sponsored by the European Association for Theoretical Computer Science (EATCS). This annual conference series covers all important areas of theoretical computer science, such as computability, automata, formal languages, analysis of algorithms, computational complexity, data types and data structures, theory of data bases and knowledge bases, semantics of programming languages, program specification, transformation and verification, foundations of logic programming, theory of logical design and layout, parallel and distributed computation, theory of concurrency, symbolic and algebraic computation, term rewriting systems, computational geometry, cryptography, and theory of robotics. This volume contains five invited papers and 52 papers selected from 250 submitted.