Abstract: A polyetherimide-based foam contains specific amounts of a nucleating agent and a polyetherimide having a weight average molecular weight of 30,000 to 80,000 grams per mole and a dispersity of 2.7 to 4.5. The foam has a density of 20 to 60 kilograms per meter3, and a closed cell content of 80 to 100 percent. The foam can be prepared by a method that combines the nucleating agent and polyetherimide with a blowing agent that includes specific amounts of acetone and methanol. Also described are articles that include the foam.