This book constitutes revised selected papers from the 6th International Conference on Arabic Language Processing, ICALP 2017, held in Fez, Morocco, in October 2017. The 18 full papers presented in this volume were carefully reviewed and selected from 55 submissions. They were organized in topical sections named: machine translation systems; speech recognition and synthesis; text categorization, clustering, and summarization; information retrieval systems; and Arabic NLP tools and applications.