Missing children who are not found quickly are at an increased risk of victimization. The National Child Search Assistance Act, as amended, requires that within 2 hours of receiving a missing child report, law enforcement agencies (LEAs) enter the report into the Department of Justice’s (DOJ) National Crime Information Center (NCIC), a clearinghouse of information instantly available to LEAs nationwide. DOJ’s Criminal Justice Information Services (CJIS), the CJIS Advisory Policy Board (the Board), and state criminal justice agencies share responsibility for overseeing this requirement. As requested, GAO examined (1) CJIS’s and the Board’s efforts to implement and monitor compliance with the requirement; and (2) selected LEA-reported challenges with timely entry and DOJ’s actions to assist LEAs in addressing them. GAO reviewed documents, such as agency guidelines, and interviewed officials from DOJ, six state criminal justice agencies, and nine LEAs selected in part based on missing children rates. The results are not generalizable to all states and LEAs, but provided insights on this issue. CJIS and the Board have taken steps to help ensure implementation of the 2-hour entry rule, but could strengthen their oversight to better assure compliance with the rule. Starting in 2007, CJIS: (1) informed all state criminal justice agencies that LEAs will have 2 hours to enter reports of missing children into NCIC once they have collected the required data (e.g., child’s biographical information); (2) provided guidance on how LEAs could document compliance with the rule; and (3) informed state criminal justice agencies that the Board had authorized CJIS to begin assessing compliance with the rule in audits starting in 2009. To help ensure compliance among all NCIC users, CJIS and the Board require state criminal justice agencies to audit all LEAs in the state that enter data into NCIC. However, CJIS and the Board have not taken steps to establish minimum audit standards for state criminal justice agencies to use in assessing LEAs’ compliance with the 2-hour rule. In the absence of such standards, the selected six state criminal justice agencies GAO contacted used varied approaches to assess LEAs’ compliance. For example, two were not using the 2-hour criterion, and the number of missing children records the six agencies reviewed to assess timeliness ranged from all records in one state to no records in another. The fact that the state agencies did not consistently apply the 2-hour criterion to review a sample of missing children records raises questions about the reliability of the information the agencies collect on LEA compliance. Establishing minimum standards for state agency audits could help provide CJIS with reasonable assurance that the audits contain reliable information on LEA compliance. Officials from eight of nine LEAs GAO contacted reported challenges to entering information on missing children into NCIC within 2 hours; CJIS and the Office of Juvenile Justice and Delinquency Prevention (OJJDP) could use existing mechanisms to obtain and share information on challenges. Seven LEAs reported challenges determining whether a child is missing when there are custodial disputes. Six LEAs reported challenges obtaining information from child welfare agencies on missing children in the child welfare system. Officials from child welfare agencies in areas where LEAs reported this challenge said that they may not always have the information LEAs need, and are taking steps to ensure timely communication between their staff and LEAs. In association with the National Center for Missing and Exploited Children and other stakeholders, in 2006 OJJDP developed (1) a model policy stating that LEAs will accept reports of missing children even when custody has not been established and (2) sample self-assessments so LEAs could enhance their responses to missing children in the child welfare system. However, eight of the nine LEAs stated that these challenges persist. DOJ does not know the extent of these challenges across all LEAs and has limited capability to conduct such an assessment. By using existing CJIS and OJJDP mechanisms–such as CJIS’s training for state agencies and OJJDP-funded training for LEAs–to obtain information on the extent to which LEAs face these and other challenges and provide examples of how some LEAs have mitigated the challenges, DOJ could be better positioned to carry out its oversight of NCIC with respect to assuring compliance with the 2-hour rule. GAO recommends that CJIS and the Board consider establishing minimum standards for states to use to monitor compliance with the 2-hour rule and CJIS and OJJDP use existing mechanisms to obtain and share information on LEA challenges and successful efforts to mitigate them. DOJ concurred.