Abstract. The suburban sprawl into rural and wildland areas increases the potential for damage from mass fires, either through nuclear attack or natural disaster. But defenses against the devastating effects of mass fires suffer from lack of quantitative information on behavior of large intense fires. Laboratory-scale testing is not enough —it is very likely that a different set of controlling factors take over when a fire grows to a certain size and intensity. A series of large-scale tests using woodland fuels in ordered piles simulating built-up residential areas has been started to provide the missing data. Preliminary tests in the series are reported here.