Flammability hazards and mechanisms have been analyzed for mg-scale samples of polymers by integrating the use of a new TGA/DSC/GCMS technique, the PCFC microcalorimeter developed by Lyon, and computational quantum chemistry. The first apparatus is based on a Rheometrics STA 1500. Head space immediately above the polymer is sampled through a microprobe and heated transport line into a multiport valve of a Hewlett-Packard 5890 Series II GC with 5972 Mass Selective Detector. The PCFC microcalorimeter is based on continuous analysis of the oxygen required to consume pyrolysis gases. The two apparatus yield complementary data on the rate and composition of gases evolved in pyrolysis, and they are shown here to be in good agreement. Kinetics of decomposition are established from the data and from computed rate constants.