Copolyetherimides compositions having high glass transition temperatures and outstanding ductility are presented. The copolyetherimides having M.sub.w of at least 40,000 comprising isomeric bis(phthalimide) structural units within a relatively narrow range of isomer proportions exhibited Tgs of at least 240.degree. C. and outstanding Notched Izod values. The copolyetherimides comprise oxydianiline residues and structural units of the formulas (I) and (II) (III). The copolyetherimides are characterized by a mole percentage of structural units derived from 4,4'-biphenol in a range from about 55% to about 85% of all bisphenol-derived structural units present in the copolyetherimide composition; a mole percentage of structural units derived from bisphenol A in a range from about 45% to about 15% of all bisphenol-derived structural units present in the copolyetherimide composition; and a total mole percentage of structural units derived from bisphenol A or 4,4'-biphenol of at least 95% of all bisphenol-derived structural units present in the copolyetherimide composition.