A polyetherimide composition includes specific amounts of a polyetherimide, a block polyestercarbonate, a block poly-carbonate-polysiloxane, and a core-shell impact modifier in which the core includes a polysiloxane and the shell includes a poly(alkyl (meth)acrylate). Relative to a corresponding composition lacking the core-shell impact modifier, the polyetherimide composition exhibits increased impact strength while substantially retaining flame retardancy. Also described are associated articles, including articles formed by additive manufacturing, and a method of additive manufacturing.