Abstract This paper presents a selective ten year review of the Binghamton State Office Building (BSOB) transformer incident. Contamination of the building with polychlorinated biphenyls (PCBs), chlorinated benzenes, and pyrolytic conversion products including polychlorinated dibenzodioxins and dibenzofurans (PCDDs and PCDFs) occurred during a 30 minute fire. This became the first incident of its type to be recognized and to demonstrate a “real world” conversion of PCBs and chlorinated benzenes to dibenzofurans and dioxins. Cleanup and rehabilitation funds of $40 million have been appropriated and cleanup is still ongoing over ten years after the fire for the building which cost $17 million to construct. The reentry criteria established have still not been met in all parts of the building. Persistence of elevated chemical levels in certain localized areas prevents reoccupancy at this time.