An amine-functional styrene-acrylonitrile (SAN-amine) polymer is proposed as a reactive compatibilizer for bisphenol-A-polycarbonate/acrylonitrile-butadiene-styrene (PC/ABS) blends. This polymer should be miscible with the styrene/acrylonitrile (SAN) copolymer matrix of ABS materials, and the pendant secondary amine groups should react with PC at the carbonate linkage to form a SAN-g-PC copolymer. The graft copolymer molecules should reside at the PC/ABS interface and provide improved morphological stability at elevated temperatures by suppressing phase coalescence. This paper describes the synthesis of this reactive compatibilizer and its reaction with carbonate moieties. Characterization of this reaction was done by nuclear magnetic resonance spectroscopy and gel permeation chromatography using model secondary amine and carbonate-containing compounds to facilitate the investigation. The morphology of compatibilized and uncompatibilized PC/SAN blends was examined by transmission electron microscopy.