The paper discusses the monitoring of woodstove performance under field conditions in 34 Northeast U.S. houses for two heating seasons, and in 8 Northwest U.S. and 14 Whitehorse, Yukon, Canada, houses for one heating season. Stoves included models certified or capable of being certified to Oregon Department of Environmental Quality and U.S. EPA standards. Objectives of the studies were to evaluate the performance of advanced technology stoves (catalytic, noncatalytic low emission, and catalytic add-on/retrofit devices) relative to conventional technology stoves. Stoves were monitored for particulate emissions, wood use, and creosote accumulation in flue systems. The new technology stoves models showed the potential to reduce particulate emissions, fuel use, and creosote accumulation. Good performance in at least one installation for most of the stove models indicates that factors such as stove maintenance and fuelling practices, as well as technology factors, are important in reducing emissions. Reducing firebox size appears to be a consistent factor in reducing emissions.