Carbonaceous compounds are a significant component of fine particulate matter (PM2.5), contribute to health effects and regional haze, and influence the earth's radiation balance. Understanding the sources of particulate carbon is necessary to mitigate its adverse effects. A backward Lagrangian particle dispersion chemical transport model (CTM) was developed to simulate PM2.5 total carbon (TC) concentrations and the contributions from wildfire, vegetation, mobile, area, and other sources at individual receptor sites. This model was used to simulate TC at IMPROVE monitoring sites from 2006 through 2008. The simulations were conducted using emissions from the 2002 Western Regional Air Partnership (WRAP) regional haze inventory for all years. Wildfires vary significantly from one year to another, so the National Center for Atmospheric Research (NCAR) biomass burning inventory, derived from moderate resolution imaging spectroradiometer (MODIS) satellite data, was used for the modeled years. The Lagrangian model used pseudo-first-order rate equations in which the physical and chemical rate coefficients were derived by tuning the model to fit the Interagency Monitoring of Protected Visual Environments (IMPROVE) 2008 TC concentrations and secondary organic carbon fractions. Contributions of biomass burning to TC during 2006 were also available from the Community Multiscale Air Quality (CMAQ) Eulerian CTM, operated by the Environmental Protection Agency. In this presentation, the biomass burning contributions from the two 2006 model runs are compared, and seasonal and spatial patterns of the source contributions from 2006 through 2008 are presented. During the summer months, the TC was predominantly due to biomass burning and secondary organic carbon from vegetation. Smaller contributions from area and mobile sources also occurred. During the winter months, vegetation and biomass burning had smaller contributions, while the relative contributions from mobile sources increased, and area sources were the largest contributor, accounting for about half of the TC. Different fire seasons were also evident, with large contributions during the summer months due to wildfires and smaller contributions during the spring and fall when prescribed and agricultural fires regularly occur.