Specific biomolecular interactions occur in practically every bio- logical process, usually involving macromolecules such as proteins and nucleic acids. Thus, it is not surprising that great attention has been devoted by biologists, chemists, and physical chemists to the general phenomenon of macromolecular recognition in order to gain a better understanding of the principles, forces, and energetics that de- termine the often remarkable specificities of such interactions as those of enzymes and their substrates and inhibitors, antibodies with anti- gens, hormones with their receptors, and DNA with drugs. These studies have allowed the unraveling of some basic principles of mol- ecular recognition, such as complementarity, specificity, and dynam- ics of the interacting species, and at the same time have led to development of analytical and separation techniques based on bio- logical specificity (e. g. , affinity chromatography and other bioaffinity methods). This volume was assembled to address current research and developing ideas in biomolecular recognition through the contribu- tions presented at the Conference on Mechanisms of Recognition in Biological Macromolecules held in Siena, Italy, September 4-6,1986. The Conference was cosponsored by the National Research Council of Italy, the Italian Biochemical Society, the University of Siena, and the International Interest Group in Biorecognition Technology.