Version 3 of the Biogenic Emissions Inventory System (BEIS3) has been implemented as part of an upgrade to EPA's Community Multiscale Air Quality (CMAQ) modeling system. BEIS3 contains several improvements over BEIS2: (1) a 1-km vegetation database for the contiguous United States, which resolves canopy coverage by tree species; (2) normalized emission factors for 34 chemical species, including 14 monoterpene compounds; (3) a soil nitric oxide emissions algorithm that accounts for soil moisture, crop canopy coverage, and fertilizer activity; and, (4) speciation factors for the CBIV, RADM2, and SAPRC99 chemical mechanisms. This paper will compare volatile organic compound (VOC) and NO emission estimates from BEIS2 and BEIS3 for a seven-day period during July 1999. In addition, the paper will provide preliminary comparisons of modeled concentrations for several photochemically-important compounds, including ozone, formaldehyde, and isoprene resulting from simulations with CMAQ.