The Fourth Colloquium on Automata, Languages and Programming was preceded by similar colloquia in Paris (1972), SaarbrUcken (1974) and Edinburgh (1976), all sponsored by EATCS (European Association for Theoretical Computer Science). Because of the growing interest in these broadlybased colloquia on theoretical computer science, it has been planned by EATCS to organize a colloquium in this series every year from now on. This seems justified also in view of the fact that some 190 papers, among them some of very high quality, were submitted to this Fourth Colloquium, in spite of the fact that there are exceptionally many conferences in theoretical computer science during 1977.