There are a number of sources of biomass-derived and fossil fuel-derived CO2 emissions from pulp and paper mills. The CO2 emissions from kraft mill lime kilns can be difficult to properly characterize because they contain a combination of fuel- and process-derived carbon of both fossil and biomass origin. In this paper, methods are presented for estimating biomass-derived and fossil fuel-derived emissions Of CO2 from kraft mill lime kilns. It is shown that an accurate industry-wide estimate of greenhouse gas emissions from kraft mill lime kilns can be developed considering only the fossil fuel burned in these kilns. These emissions are estimated to be 1.3 million metric ton carbon equivalents (MMTCE) per year, or approximately 7% of direct emissions from the pulp and paper industry. Individual mills may need to consider more than just fossil fuel consumption in estimating greenhouse gas emissions due to a variety of site-specific factors, including the on-site manufacture of precipitated calcium carbonate (PCC) from lime kiln stack gases.