In the 1930s there was a considerable interest in the possibility that chemical and biological weapons might be used in the war which many people realized was impending. When such weapons were not, in fact, used in the war, public interest in their potentialities died down and the use of thermonuclear weapons diverted the attention of those who would otherwise have been concerned with chemical and biological warfare by focussing it on the urgent need to prevent any further use of these catastrophic new armaments. From time to time there have been outbursts of indignation when reports of the use of gas or microbial agents have been made public but there has been little study outside military circles of the potentialities or implications of their use. During the past year or so, however, there has been a recrudescence of public interest in the subject. There have been many reasons for this but, undoubtedly, the international conference on chemical and biological warfare held in London last February under the auspices of the J. D. Bernal Peace Library had a stimulating effect. The contributors to this conference were able to speak authoritatively on various topics connected with chemical and biological warfare as they were mostly senior scientists, some with world-wide reputations, working in related fields, or else younger people who, for one reason or another, had made a special study of some aspect of the subject. Furthermore, the conference received considerable publicity on radio and television and in the newspapers and gave rise to questions in the House of Commons which, in turn, received publicity and helped to keep public interest alive.