From fiscal years 2006 through 2010, the Department of Homeland Security (DHS) has awarded nearly $1.7 billion dollars to port areas through its Port Security Grant Program (PSGP) to protect critical maritime infrastructure and the public from terrorist attacks. The Federal Emergency Management Agency (FEMA)??a DHS component agency??is the agency responsible for distributing grant funds. GAO was asked to evaluate the extent to which DHS has (1) allocated PSGP funds in accordance with risk; (2) encountered challenges in administering the grant program and what actions, if any, DHS has taken to overcome these challenges; and (3) evaluated the effectiveness of the PSGP. To address these objectives, GAO reviewed the PSGP risk model, funding allocation methodology, grant distribution data, and program documents, such as PSGP guidance. Additionally, GAO interviewed DHS and port officials about grant processes, funding distribution, and program challenges, among other things.