Aryl tetramethylphosphorodiamidates were effectively ortho-lithiated with sec-BuLi in tetrahydrofuran at -105°C.The resulting lithiated species were trapped with a variety of electrophiles at -105°C to provide ortho-substituted phosphorodiamidates. When the lithiation was carried out at -78°C, O→C migration of the bis(dimethylamino)phosphoryl group took place rapidly and 2-hydroxyarylphosphonic tetramethyldiamides were produced regioselectively. The ortho-directing ability of the phosphorodiamidates was investigated by intermolecular competition experiments with other directed metalation groups.