As international aid workers continue to descend upon Port-au-Prince they confront a human disaster that is both unique to Haiti and grimly familiar. Disaster response is tailored to the details of each emergency as it unfolds on the ground. But reports from previous relief efforts--like the response to the Asian tsunami that killed some 225,000 people in 12 countries in 2004--give a picture of practices that allow relief efforts to work quickly and effectively, as well as those that result in waste and delays.