We compared reports of increased substance use in Manhattan 1 and 6 months after the September 11, 2001, terrorist attacks. Data from 2 random-digit-dial surveys conducted 1 and 6 months after September 11 showed that 30.8% and 27.3% of respondents, respectively, reported increased use of cigarettes, alcohol, or marijuana. These sustained increases in substance use following the September 11 terrorist attacks suggest potential long-term health consequences as a result of disasters.