These excellent reports have been professionally converted for accurate flowing-text e-book format reproduction. The first report deals with the transnational threat from two predominantly Latino gangs, Mara Salvatrucha (MS-13) and the 18th Street gang (M-18), which have raised concern among policy makers for a number of reasons:(1) membership in these gangs has spread from the Los Angeles area to other communities across the United States; (2) these gangs are considered "transnational," primarily because MS-13 and M-18 cliques are being established in Central America and Mexico; (3) there are reports suggesting that these gangs are engaged in criminal enterprises normally associated with better organized and more sophisticated crime syndicates; and (4) MS-13 and M-18 gang members may be involved in smuggling operations and, by extension, could potentially use their skills and criminal networks to smuggle terrorists into the United States. To date, however, no evidence exists establishing a link between MS-13 and M-18 members and terrorists. Nevertheless, some observers maintain that these two gangs may develop the capacity to become organized criminal enterprises capable of coordinating illegal activities across national borders. Yet, others find them to be no more criminally organized or sophisticated than other street gangs. At issue for Congress is whether the MS-13 and M-18 gangs constitute an emerging transnational criminal threat.The second report deals with the issue of unaccompanied alien children (UAC). After several years of increases, the number apprehended at the Southwest border by the Department of Homeland Security's (DHS's) Customs and Border Protection (CBP) peaked at 68,541 in FY2014. Some Members of Congress as well as the Obama Administration have characterized the issue as a humanitarian crisis. The reasons why they migrate to the United States are often multifaceted and difficult to measure analytically. The Congressional Research Service (CRS) has analyzed several out-migration-related factors, such as violent crime rates, economic conditions, rates of poverty, and the presence of transnational gangs. CRS also has analyzed in-migration-related factors, such as the search for economic opportunity, the desire to reunite with family members, and U.S. immigration policies.