Since September 11, 2001, a concern has been that terrorists or their supporters would seek to immigrate to the United States (I.e., seek lawful permanent residency (LPR)). The Department of Homeland Security's U.S. Citizenship and Immigration Services (USCIS) conducts background checks and the FBI conducts name checks for those applying for LPR. GAO was asked to review USCIS's processes for screening individuals applying for LPR. GAO assessed: (1) what available data show about the extent to which national security concerns were discovered during USCIS background checks for LPR applications, (2) what issues USCIS has encountered in its background check processes and what actions have been taken to resolve those issues, and (3) the extent to which USCIS has addressed fraud vulnerabilities in its adjudication procedures for LPR. To conduct this work, GAO analyzed USCIS background check and adjudication procedures, USCIS data on adjudications, and its assessments of fraud in applications for LPR, and interviewed USCIS and FBI officials. GAO recommends that the Director of USCIS (1) establish timetables for addressing findings from its four benefit fraud assessments, and (2) establish requirements in LPR adjudications procedures on what evidence petitioner should be verified.