Low density joint compounds, and methods for their use are disclosed. Joint compounds comprising water, calcium carbonate, a foaming agent, and a rheology modification agent contain a plurality of stable air bubbles. Joint compounds can have densities of about 4 pounds per gallon to about 8 pounds per gallon. A presently prepared composition has a density of about 4.8 pounds per gallon. A presently preferred foaming agent is a polyether siloxane copolymer. A presently preferred rheology modification agent is poly(ethylene oxide). The joint compounds can comprise additional components such as perlite, mica, talc, preservatives, and latex.