Subterranean termites, Reticulitermes spp., were attracted to carbon dioxide (CO₂) in laboratory and field tests. In behavioral bioassays, Reticulitermes flavipes (Kollar), Reticulitermes tibialis Banks, and Reticulitermes virginicus Banks were attracted to CO₂ concentrations between 5 and 50 mmol/mol. In further bioassays, R. tibialis and R. virginicus were attracted to the headspace from polyisocyanurate construction foam that contained 10–12 mmol/mol CO₂. In soil bioassays in the laboratory, more termites foraged in chambers containing CO₂-generating formulations than in unbaited control chambers. In field tests, stations containing CO₂-generating baits attracted R. tibialis away from wooden fence posts at rangeland sites in Colorado. For all of the CO₂ formulations tested, termites foraged in significantly more bait stations at treatment fenceposts than in bait stations at the control fenceposts. By the end of the 8-wk study, the number of bait stations located by termites at treatment fenceposts ranged from 40 to 90%. At control fenceposts, termites foraged in only a single station and the one positive station was not located by termites until week 5 of the study. At treatment fenceposts, termites foraged equally in active stations (containing a CO₂-generating bait) and passive stations (with no CO₂-generating bait), indicating that bait stations may benefit passively from a proximal CO₂ source in the soil. CO₂ used as an attractant in current baiting systems could improve their effectiveness by allowing earlier exposure of termites to an insecticide.