Findings showed that undocumented aliens accounted for 12 percent of the arrests in San Diego and 15 percent in El Paso during the period studied. The costs for criminal justice processing of these undocumented persons in San Diego were just over $15 million. Findings indicated that local effective responses to criminality are hampered by systemwide problems that include jail crowding and limited resources. Results indicated the need for increased Federal assistance in border counties to allow local justice efforts to be more effective. The assistance should consist of increased resources for the Border Patrol and the development of a mechanism to identify and analyze trends related to undocumented persons in the offender population. Figures, tables, reference lists, and appended data tables and background information.