A solution of a poly(phenylene ether) copolymer derived from 2-methyl-6-phenylphenol and a dihydric phenol in a non-halogenated solvent is useful in curable compositions. The copolymer has less than 0.5 weight percent monohydric phenols having identical substituents in the 2- and 6-positions of the phenolic ring, and an absolute number average molecular weight of 1,000 to 10,000 grams/mole. A solution of a poly(phenylene ether) copolymer derived from 2-methyl-6-phenylphenol, 2,6-dimethylphenol, and a dihydric phenol in a non-halogenated solvent is also useful in curable compositions. This copolymer has an absolute number average molecular weight of 1,000 to 5,000 grams/mole. A cured composition is obtained by heating curable compositions composed of the poly(phenylene ether) copolymer solutions and thermoset resins for a time and temperature sufficient to evaporate the non-halogenated solvent and effect curing. The compositions can be used for preparation of composites for printed circuit boards.