The boundary between the Triassic and Jurassic periods and systems has long been recognized to coincide with some of the most remarkable events in the Mesozoic. Here I briefly review the synchronous mass extinction in marine and terrestrial ecosystems, global greenhouse warming, and major perturbations in the carbon cycle recorded in carbon isotope excursions, as signals of linked changes in the Earth system. Extensive continental flood basalt volcanism ofthe Central Atlantic Magmatic Province is likely to have triggered all these events, starting a cascade of environmental and biotic crises. Recent studies by our research team in stratigraphic sections in Hungary and Austria have also contributed to the development of models ofTriassic-Jurassic boundary events. The Global Stratotype Section and Point for the Triassic-Jurassic boundary has recently been defined in the Kuhjoch section (Tyrol, Austria) at the first appearance of the ammonite Psiloceras spelae. This level slightly postdates the main changes in this and other correlative sections.