Data from the 2000 and 2001 National Household Surveys on Drug Abuse were used for this report. The primary focus was New York City (NYC) and the New York Consolidated Metropolitan Statistical Area (NY CMSA). For comparison purposes, the report also looked at trends in a composite of areas surrounding Los Angeles, Chicago, and Detroit (Consolidated Metropolitan Statistical Areas or C-CMSA). The goal of the study was to determine whether the events were associated with changes in the prevalence of substance use or mental health problems in these areas. Results indicate relatively few significant changes in problematic behavior in general following September 11. Because the post-September 11 data were collected from October through December 2001, there might be a lag effect in which behavioral influences are not apparent until a greater amount of time has passed. Highlights of the findings include: an increase in youths aged 12 to 17 using non-medical psychotherapeutic drugs; double the rate of past month use of marijuana by males aged 12 or older; and no change in the overall prevalence of past month alcohol use. In NYC and NY CMSA, there were no changes in reporting of past month, past year, or current substance abuse treatment utilization among persons aged 12 or older following September 11, 2001. There were no statistically significant increases or decreases following September 11 in the proportion of adults classified with distress or a disorder. The percentage of the population aged 12 or older living in NYC, the NY CMSA, or the C-CMSA reporting that religion was “very important” in their lives did not differ. 5 figures, 59 tables, 25 references, 5 appendices