Since implementation of the Screening Partnership Program (SPP) in 2004, 29 airports have applied to the program, citing various advantages and relatively few disadvantages. Of the 25 approved, 16 are participating in the program, 6 are currently in the contractor procurement process, and the remainder withdrew from participation because their commercial airline services were discontinued. In 2011, the Transportation Security Administration (TSA) denied applications for 6 airports because, according to TSA officials, the airports did not demonstrate that participation in the program would "provide a clear and substantial advantage to TSA security operations." After enactment of the Federal Aviation Administration Modernization and Reform Act of 2012 (FAA Modernization Act) in February 2012, TSA revised its SPP application, removing the "clear and substantial advantage" question. Four of the 6 airports that had been denied in 2011 later reapplied and were approved. In GAO's survey and in interviews with airport operators (of SPP and non-SPP airports) and aviation stakeholders, improved customer service and increased staffing flexibilities were most commonly cited as advantages or potential advantages of the SPP. Individual Federal Security Directors we interviewed cited reduced involvement in human resource management as an advantage; however, TSA generally remains neutral regarding the SPP. Few disadvantages were cited; however, some airport operators cited satisfaction with federal screeners and concerns with potential disruption from the transition to private screening services. TSA has developed some resources to assist SPP applicants; however, it has not provided guidance to assist airports applying to the program. Consistent with the FAA Modernization Act, TSA's revised SPP application requested that applicants provide information to assist TSA in determining if their participation in the SPP would compromise security or detrimentally affect the cost-efficiency or screening effectiveness of passengers and property at their airport. TSA also developed responses to frequently asked questions and has expressed a willingness to assist airports that need it. However, TSA has not issued guidance to assist airports with completing applications and information on how the agency will assess them. Three of five airport operators who applied using the current application stated that additional guidance is needed to better understand how to respond to the new application questions. Developing guidance could better position airports to evaluate whether they are good candidates for the SPP. TSA recently improved its screener performance measures, but could benefit from monitoring private versus federal screener performance. In April 2012, TSA added measures to ensure that the set of measures it uses to assess screener performance at private and federal airports better addresses its airport screening strategic goals and mission. However, TSA does not monitor private screener performance separately from federal screener performance. Instead, TSA conducts efforts to monitor screener performance at individual SPP airports, but these efforts do not provide information on SPP performance as a whole or across years, which makes it difficult to identify program trends. A mechanism to consistently monitor SPP versus non-SPP performance would better position TSA to ensure that the level of screening services and protection provided at SPP airports continues to match or exceed the level provided at non-SPP airports, thereby ensuring that SPP airports are operating as intended.