The concept, crisis escalation, has three distinct bu: closely-related meanings: change from incipient to full-scale crisis; change from non-violence to violence; and change from no/low violence to severe violence. These are examined through a model of crisis escalation and a group of seven hypotheses derived from the model. Testing of the propositions on crisis escalation with the evidence from 388 international crises and 829 foreign policy crises from the end of 1918 to the end of 1988 reveals strong support for most of the postulated linkages in the crisis escalation model. Moreover, the evidence from ten in-depth case studies indicates a widely shared pattern of coping with high stress, despite notable diversity in crisis attributes. This finding challenges conventional wisdom about how states cope with foreign policy crises.