Technical Abstract: Greenhouse gas (GHG) emissions and their potential impact on global warming has become an important national and international concern. Dairy production systems along with all other types of animal agriculture are recognized as a source of GHG. Although little information exists on the net GHG emissions from dairy farms, recent press coverage has portrayed livestock production as a "stealth threat" and major contributor to environmental problems at a local and global scale. The Dairy Greenhouse Gas Model (DairyGHG) was developed to estimate the net GHG emissions from dairy production systems. DairyGHG uses partial life cycle assessment methodology to account for CH4, N2O, and CO2 emissions and sinks in the dairy production system. The global warming burden of the net CH4, N2O, and CO2 emitted from the farm (including that emitted in the production of farm inputs) is accounted for in CO2 equivalent units (CO2e) and divided by the total milk produced to provide a normalized carbon footprint. The DairyGHG model suggests that the carbon footprint of milk produced by most dairy farms is in the range of 0.5 to 0.8 kg CO2e per kg of milk. By using a more comprehensive assessment of the full carbon cycle of farms, DairyGHG's estimates of the carbon footprint of milk production are about half that reported in recent literature.