Book excerpt: This book constitutes the refereed proceedings of the Second International Conference on Modeling Decisions for Artificial Intelligence, MDAI 2005, held in Tsukuba, Japan in July 2005. The 40 revised full papers presented together with an introduction by the editors and 4 invited lectures were thoroughly reviewed and selected from 118 submissions. The papers are devoted to theory and tools for modeling decisions, as well as applications that encompass decision making processes and information fusion techniques. Special focus is given to applications related with risk, security and safety.