Although reliable data on gang activity in the five countries is limited, the number of gang members in Central America and Mexico range from a conservative estimate of 50,000 to approximately 305,000. Crime and gang violence is threatening economic and democratic development across the region. The U.S. Government must work with the governments of these five countries in developing an interagency and international strategy for dealing with the transnational criminal activities of gangs. In these efforts, law enforcement must be balanced with prevention/intervention efforts. An effective criminal justice response to gangs in the five countries requires that all components of their criminal justice systems be strengthened. All features of a comprehensive international effort to counter gangs and their criminal activities must be evaluated to determine their effectiveness. This, in turn, requires that accurate information on gangs and gang violence be developed in each country. Criminal gangs like MS-13 and 18th Street are engaged in international criminal activities that include kidnapping, robbery, extortion, assassinations, and trafficking in people and contraband across borders. Gang members who commit crimes in their own countries often escape to the United States, where they continue criminal activity until they are caught and deported. This often becomes a cycle. Current policies and programs for addressing the gang problem across Central America and Mexico lack cooperation and coordination. This study involved field teams and local researchers in each country, as well as the United States, the teams conducted interviews with various stakeholders, including vulnerable youth, gang members, and former gang members. 2 tables, 3 figures, and appended list of individuals and organizations consulted in the United States