The report summarizes wood stove particle size and chemical composition data gathered to date. (NOTE: In 1995, EPA estimated that residential wood combustion (RWC), including fireplaces, accounted for a significant fraction of national particulate matter with aerodynamic diameters < 2.5 micrometers (PM2.5) and air toxics emissions. Based on very limited wood stove particle size data, it has been assumed that the particulate emissions are 100% PM2.5.) Tests are being conducted in a RWC laboratory burning oak cordwood in a test protocol designed to mimic in-home operation. Since all RWC wood smoke particles < 10 micrometers (PM10) are thought to be the result of condensation, their distribution and total mass are influenced by collection temperature. In tests completed to date, no attempt was made to control collection temperature. Thus these results probably represent the lower bound. The PM10 and PM2.5 fractions would probably be higher at typical winter temperatures. The particles collected on the first stage (cutpoint = 11.7 micrometers) are light gray and appear to include inorganic ash. Particles collected on the remainder of the stages are black and appear to be condensed organics. Total particulate emission rates range from 4 to 61 g/hr; emission factors range from 2.8 to 41 g/kg of dry wood burned.