this book constitutes the refereed proceedings of the 6th international colloquium on grammatical inference, icgi 2002, held in amsterdam, the netherlands in september 2002.the 28 revised full papers presented together with 7 software descriptions were carefully reviewed and selected from 48 submissions. the papers address issues in machine learning, automata, theoretical computer science, computational linguistics, and grammar systems as well as applications in fields like natural language processing, pattern recognition, computational biology, information retrieval, text processing, and data compression.