The impact of exposure to the World Trade Center attack on children presenting separation anxiety disorder (SAD) 6 months after the attack was studied in a representative sample of New York City public school students (N = 8,236). Probable SAD occurred in 12.3% of the sample and was more frequent in girls, young children, and children who previously had been exposed to traumatic situations. Probable SAD was highly comorbid with probable posttraumatic stress disorder (PTSD). Direct exposure to the attack or to television coverage of the attack was associated with probable SAD or number of SAD symptoms, whereas proximity to Ground Zero or family member exposure were not. The identified pattern of associations existed independently of a child having probable PTSD. SAD should be considered among the conditions likely to be found in children after a large-scale disaster.