The carbon-nitrogen bond of carboxamides is extremely stable under most conditions. The present study reveals that simple zirconium- and hafnium-amido complexes are highly efficient catalysts for equilibrium-controlled transamidation reactions between secondary amines and tertiary amides. In a number of cases, transamidation proceeds rapidly at room temperature. We find that these new catalysts are sufficiently active to promote the metathesis of tertiary amides, which arises from successive transamidation cycles. The catalytic activities we observe are unprecedented and represent a substantial step toward a long-range goal of conducting equilibrium-controlled reactions with carboxamides.