This report is part of the Youth Crime Gun Interdiction Initiative, a 17-city demonstration project aimed at reducing youth firearms violence. For the purpose of this project, a "crime gun" is defined as "any firearm that is illegally possessed, used in a crime, or suspected by enforcement officials of being used in a crime." As part of providing crime gun trace information for a 10-month period, this report contains analyses of requests for crime gun traces; analyses of successful NTC traces; analysis of incomplete traces; and analyses by adult, youth, and juvenile age categories. The findings for the 17 cities show that firearms rapidly diverted from first retail sales at federally licensed gun dealers to an illegal market account for at least one-quarter of the firearms that police recover from juveniles (17 years old and under) and youth (ages 18-24). One out of 10 firearms recovered by police is from a juvenile; when youth are included, the number changes to 4 out of 10. In 15 of the 17 sites, the majority or the single largest supply of the crime guns successfully traced comes from retail sources within the State. Jersey City and Washington, D.C., are the only sites where the largest single source of successfully traced crime guns is outside of their State or borders. Seven out of 10 crime guns recovered from adults are handguns; for juveniles and youth, the number is 8 out of 10. Half of all crime guns recovered by police are semiautomatic pistols, which are also the preferred weapons for juvenile and youthful offenders (60 percent). Although thousands of various kinds of firearms are available, crime guns are concentrated among a relatively small number of makes and calibers in each city. Preliminary research shows that a high percentage of crime guns with obliterated serial numbers were originally purchased as part of a multiple sale by a federally licensed gun dealer and then illegally trafficked. During the course of the initiative, trace requests from the 17 sites nearly doubled over the same period the previous year, from 20,000 to more than 37,000 requests. Reports for each of the 17 sites are provided. For the full reports for each site, see NCJ-167917-167932.