Roger G. Johnston has been head of the Vulnerability Assessment Team @Los Alamos National Laboratory (LANL) since 1992. He received a B.A. from Carleton College in 1977, and M.S. and Ph.D. degrees in physics from the University of Colorado in 1983. Johnston has authored more than 90 technical papers and 45 invited talks and holds 10 U.S. patents. He has won numerous awards, including the 2004 LANL Fellows Prize for Outstanding Research. Address: Los Alamos National Laboratory, MS J565, Los Alamos, NM 87545. Internet: rogerj@lanl.gov