The weldabilities of two commercial blends of polycarbonate (PC) and elcrylonitrile-butadiene-styrene (ABS) to themselves and to several other resins and blends are assessed through 120 Hz vibration welds of 6.35- and 3.2-mm-thick specimens. While the thicker specimens of both blends have relative weld strengths of 83%, the thinner specimens in one of the grades have a lower relative weld strength of 73%. Welds of thicker specimens of both grades to PC have relative strengths of 85%. Again, welds of thinner specimens of one of the grades to Pc have a lower relative strength of 68%. Welds of the thinner specimens of this grade with AES have relative strengths of 85%. Welds of this material with: poly(butylene terephthalate) (PET), a PC/PBT blend, modified poly(phenylene oxide), and a poly(phenylene oxide)/polyamide blend, have relative weld strengths of 45%, 26%, 76%, and 20%, respectively.