This is the first review of all the major mass extinctions in the history of life. It covers all groups of organisms - plant, animal, terrestrial, and marine - that have gone extinct alongside the geological and sedimentological evidence for environmental changes during the biotic crises. All proposed extinction mechanisms - climate change, meteorite impact, volcanisms - are critically assessed. The demise of the dinosaurs has been amply discussed, but this is the first time that this event has been put into the proper context of other extinction events.