The report describes the development of a biogenic emissions inventory for the U.S. and Canada, to assess the role of biogenic emissions in ozone formation. Emission inventories were developed at hourly and grid (1/4 x 1/6 degree) levels from input data at the same scales. Emissions were calculated as a function of biomass density and meteorological parameters (solar radiation, cloud cover, temperature, windspeed, and relative humidity). These factors were applied to a forest canopy algorithm that simulated processes generating biogenic emissions from foliage. Resultant emissions were aggregated to monthly, seasonal, and annual levels, and spatially to counties and states. (NOTE: Historically, ozone control programs based on reductions of known anthropogenic volatile organic compound (VOC) emissions have had limited success in obtaining the National Ambient Air Quality Standard. Researchers have, therefore, been actively evaluating VOC emission sources not routinely considered in ozone control strategies. One potentially large source of reactive VOCs is thought to be emissions from crop and forest foliage.) Approximately 50% of the biogenic hydrocarbon emissions occur in the summer, approximately equal amounts (20%) in the spring and fall, and much lower amounts in the winter.