The ILUTE (Integrated Land Use, Transportation, Environment) model system is an agent-based microsimulation model for the Greater Toronto-Hamilton Area (GTHA) in which disaggregate, process-based models of spatial socio-economic processes are used to evolve the GTHA system state from a known base case to a predicted future year end state in one-year time steps. ILUTE has reached a state of operational implementation in which historical validation runs are being undertaken. A 100% GTA population of persons, families, households and dwelling units has been synthesized for the year 1986. Twenty-year historical simulations (1986-2006) have been run, with model outputs being compared to Canadian Census data and Transportation Tomorrow Survey (TTS) data for 1991, 1996, 2001 and 2006. This paper presents recent findings from these historical validation tests, with particular emphasis on the systems modelling of demographic evolution of the population and of the regions housing market.