This document summarizes Heather Lea Moulaison's presentation at the ASIS&T Annual Meeting on October 26, 2010. The presentation compared how geographic locations in the Muslim West are classified in the Dewey Decimal Classification system (DDC) and the Ibn Rushd Thesaurus (IRT). Moulaison analyzed geographic terms from the IRT related to the Muslim West and compared their classification to DDC. She found that DDC was able to provide close classification for over 80% of locations in Morocco and over 90% in Spain, suggesting it can adequately classify materials for a collection focused on the Muslim West. However, the IRT grouped locations by historical areas of conquest while DDC focuses more