This book constitutes the refereed proceedings of the 13th Conference of the Spanish Association for Artificial Intelligence, CAEPIA 2009, held in Salamanca, Spain, in November 2009, in conjunction with the Workshop on Artificial Intelligence Technology Transfer, TTIA 2009.The 31 revised full papers presented were carefully selected from 125 submissions. The papers address the following topics: machine learning, multiagents, natural language, planning, diagnosis, evolutive algorithms and neural networks, knowledge representation and engineering, tutoring systems, uncertainty bayesian networks, vision, and applications.