Copolyetherimides comprise phthalimide structural units comprising both 3- and 4- linkages, wherein the designations 3-linkage and 4-linkage refer to the isomeric positions on the phthalimide ring in the totality of phthalimide-comprising structural units in the copolymer. The products have excellent properties, including high glass transition and heat distortion temperatures, high ductility and good melt flow properties, and low polydispersity.