Using electron capture, negative ionization mass spectrometry combined with high-resolution gas chromatography, we have resolved more than 120 components in technical chlordane. Components we have identified include chlorbicyclen and related compounds, compounds based on a C-11 carbon skeleton, and compounds based on a C-15 carbon skeleton. Many additional isomers of the C-10-derived compounds have also been separated and tentatively identified. X-ray crystallography was used to confirm the structures of alpha, beta, gamma, and isomer II chlordene, thus resolving conflicting reports in the previous literature. Gas chromatographic retention index data, on two different stationary phases, are presented for 147 components of technical chlordane. Electron capture, negative ion mass spectral features were used to discern structural characteristics of individual components. These data should be useful to workers interested in identifying and quantitating technical chlordane's many components wherever they are found.