This book constitutes the refereed proceedings of the 6th Ibero-American Conference on Artificial Intelligence, IBERAMIA-98, held in Lisbon, Portugal in October 1998. The book presents 32 revised full papers selected from more than 150 submissions. Also included are four invited survey papers. The papers are organized in topical sections on distributed artificial intelligence, machine learning, reasoning, vision, genetic algorithms, knowledge engineering, intelligent tutoring systems, natural language processing, neural nets, constraint programming, and planning.