Following the World Trade Center (WTC) attacks, an extensive screening survey was undertaken to assess mental health needs of New York City's school-age children. This survey demonstrated that as many as 75,000 children in New York City (10.5%) had symptoms of posttraumatic stress disorder (PTSD) and high percentages of children reported other psychiatric symptoms including depression (8.4%), anxiety (12.3%), agoraphobia (15.0%), separation anxiety (12.3%), and conduct disorder (10.9%). Rates of help-seeking by children were low, less than 33%, suggesting that highly affected children and youths were not receiving mental health services. Child and Adolescent Trauma Treatments and Services Consortium (CATS) was created in the aftermath of the WTC attacks to make high-quality evidence-based (EB) treatment available to the most highly affected children and adolescents throughout New York City and adjacent Long Island. This article presents the clinical outcomes and implementation issues of the CATS project. (Contains 1 table.)