For some time there has been a growing sense of urgency to develop and deploy effective missile defenses against a range of long and short range ballistic missile threats. Although many might believe this to be relative new to U.S. national security objectives, such interest has been ongoing since the 1960s, and many current technologies being investigated date their start to the early 1980s. This effort has been challenging technically and politically controversial. Some $110 billion has been spent since the mid-1980s; Congress appropriated $9.3 billion in FY2006. Many observers expect that the 110th Congress will review the current technology and BMD test program in 2007. This report provides a brief overview of U.S. efforts to date.