A thermoplastic composition comprising: a high heat copolycarbonate comprising 2-95 mole percent of high heat carbonate units derived from a high heat aromatic dihydroxy monomer, wherein a polycarbonate homopolymer derived from the high heat aromatic dihydroxy monomer has a glass transition temperature of 175-330°C determined by differential scanning calorimetry as per ASTM D3418 with a 20°C/min heating rate, and 5-98 mole percent of a low heat carbonate units derived from a low heat aromatic monomer, wherein a polycarbonate homopolymer derived from the low heat aromatic monomer has a glass transition temperature of less than 170°C determined by differential scanning calorimetry as per ASTM D3418 with a 20°C/min heating rate, each based on the sum of the moles of the carbonate units; and a source of added sulfur which is a sulfur-containing stabilizer compound, wherein the sulfur-containing stabilizer compound is a thioether carboxy compound, a thioether dicarboxy compound, a thioether ester compound, or a combination thereof, and wherein the sulfur-containing stabilizer compound is present in an amount effective to provide 5-50 parts per million by weight of added sulfur, based on the total parts by weight of the copolycarbonate, where the sulfur content in the copolycarbonates is determined by the methods given in the present description. a high heat copolycarbonate comprising 2-95 mole percent of high heat carbonate units derived from a high heat aromatic dihydroxy monomer, wherein a polycarbonate homopolymer derived from the high heat aromatic dihydroxy monomer has a glass transition temperature of 175-330°C determined by differential scanning calorimetry as per ASTM D3418 with a 20°C/min heating rate, and 5-98 mole percent of a low heat carbonate units derived from a low heat aromatic monomer, wherein a polycarbonate homopolymer derived from the low heat aromatic monomer has a glass transition temperature of less than 170°C determined by differential scanning calorimetry as per ASTM D3418 with a 20°C/min heating rate, each based on the sum of the moles of the carbonate units; and 2-95 mole percent of high heat carbonate units derived from a high heat aromatic dihydroxy monomer, wherein a polycarbonate homopolymer derived from the high heat aromatic dihydroxy monomer has a glass transition temperature of 175-330°C determined by differential scanning calorimetry as per ASTM D3418 with a 20°C/min heating rate, and 5-98 mole percent of a low heat carbonate units derived from a low heat aromatic monomer, wherein a polycarbonate homopolymer derived from the low heat aromatic monomer has a glass transition temperature of less than 170°C determined by differential scanning calorimetry as per ASTM D3418 with a 20°C/min heating rate, each based on the sum of the moles of the carbonate units; and a source of added sulfur which is a sulfur-containing stabilizer compound, wherein the sulfur-containing stabilizer compound is a thioether carboxy compound, a thioether dicarboxy compound, a thioether ester compound, or a combination thereof, and wherein the sulfur-containing stabilizer compound is present in an amount effective to provide 5-50 parts per million by weight of added sulfur, based on the total parts by weight of the copolycarbonate, where the sulfur content in the copolycarbonates is determined by the methods given in the present description.