In this paper we present an integer programming method for solving the Classroom Assignment Problem in University CourseTime tabling.We introduce a novel formulation of the problem which generalizes existing models and maintain stractability even for large instances. The model isvalidated through computation a lresults base do nourexperiencesat the University of Auckland,and on instances from the 2007 International Timetabling Competition.We also expand uponexistingresultsin to the computational difficulty of roomassignment problems