This volume outlines the issues raised by the military's support of biological defence research, presenting divergent views of the psychological, historical, ethical, social, legal and scientific aspects of society's attempts to protect itself from biological weapons and warfare. It is the outcome of a conference held April 4-5, 1991, and sponsored by the Center for Public Issues in Biotechnology, Maryland Biotechnology Institute, the Center for the History of Microbiology ASM Archives, the University of Maryland, Baltimore County, and Physicians for Human Rights. The first section provides an historical perspective on biological warfare, beginning with a discussion of the implications of the 1991 Persian Gulf War for biological arms control. It points out the difficulties analysts face when they attempt to ascertain the veracity of allegations of biological warfare usage. Part 1 addresses the philosophical issues of life scientists participating in defence research. It demonstrates the complexity and ambiguity of ethical issues and the difficulty in developing an unequivocal philosophical position with regard to biological defence research. Part 2 examines the Biological and Toxin Weapons Convention, paying particular attention to articles of the BWC that cover biological defence research activities. Emphasis is on the need to improve verification and build confidence in the BWC if it is to achieve effective and enduring biological arms control. Section 3 focuses on specific issues in biological defence research, mainly in the US. These papers suggest some of the difficulties in pursuing scientific research in what many consider a "gray" ethical area. The volume concludes with a discussion of the role of scientific and professional societies, particularly the American Society for Microbiology, in confronting the issues of biological warfare and defence research.