Two months before the 11 September terrorist attacks, an independent panel of experts concluded that the military9s system for developing vaccines to protect troops from anthrax, smallpox, and other exotic bioweapons "is insufficient and will fail." The report, sources tell Science, may lead to a sweeping overhaul of how the federal government develops vaccines to protect both the military and civilians from bioweapons. But developing a new suite of vaccines presents difficult scientific challenges, and testing the safety and effectiveness of preparations against lethal diseases that aren9t already widespread will be problematic.