This book constitutes the thoroughly referred post-proceedings of the 11th Conference of the Spanish Association for Artificial Intelligence, CAEPIA 2005, held in Santiago de Compostela, Spain in November 2005.

The 48 revised full papers presented together with an invited paper were carefully selected during two rounds of reviewing and improvement from an initial total of 147 submissions. The papers span the entire spectrum of artificial intelligence from foundational and theoretical issues to advanced applications in various fields.