The paper discusses studies in instrumented woodstove test laboratories to quantify woodstove emissions during operations typical of in-house usage. (The studies parallel field source sampling to identify the potential mutagenic impact of residential wood burning on ambient and indoor air.) Three woodstoves were operated over a range of burnrates, burning eastern oak, southern yellow pine, or western white pine. Two conventional stoves were tested at an altitude of 90 m. One of the conventional stoves and a catalytic stove were tested at an altitude of 825 m. For one study, tests were started after a fire had been established and encompassed several wood additions over a 6-8 hr period. The other tests were started with kindling a fire in a cold stove and continued for about 8 hours, including several wood additions. For one test, emissions were collected using a modified EPA Method 5 sampling train. For the other tests, the woodstove dilution sampling system (WSDSS) was used. As anticipated, results showed wide variability, a common problem with woodstove testing. Total particulate emissions showed the expected inverse correlation with burnrate for the conventional stoves and nearly flat for the catalytic stove. While there seemed to be little or no correlation of total particulate emissions with altitude, the sum of the PAHs quantified showed an inverse correlation with altitude.