The Office of Technology Assessment does some of the best writing on security-related technical issues in the United States, as evidenced by this excellent volume. The authors summarize the principal technologies of chemical, biological and nuclear weapons production. Purists will observe that chemical weapons are not really weapons of mass destruction, but in this context that is a quibble. The report examines the variety of pathways states may pursue to acquire these weapons. Even more important, it explains (in mercifully clear language) the variety of indicators that intelligence or inspection agencies may track to detect the production of such weapons. The discussion of the indicators or traces of proliferation efforts is good in itself, but the authors go further by discussing the ways in which proliferators can conceal evidence or mislead would-be snoopers. In short, an indispensable work.