This book results from a symposium on the theme of ‘The Physiology and Biochemistry of Plant Productivity’ which was held at the University of Calgary from July 14-18, 1980, and was jointly sponsored by the Canadian Society of Plant Physiologists and the International Association of Plant Physiologists. The subject matter of the book deals with various aspects of nitrogen and carbon metabolism, their interrelationships and interdependence. The topics covered in the chapters highlight various interesting and important lines of research that are in progress. There is no attempt to provide a comprehensive coverage of the basic physiological knowledge upon which this research depend- important references are to be found at the end of each chapter, however, and the reader will be able to pursue these as necessary. An introductory chapter by Dr. R.G.S. Bidwell (winner of the C.S.P.P. Gold Medal in 1979) considers some implications of plant physiological research and the aims and responsibilities of plant physiologists. In the next two chapters Drs. J. Rigaud and L.E. Schrader (with R.J. Thomas) elaborate on current research on nitrate metabolism and nitrogen fixation, and how an understanding of these phenomena might be usefully applied towards the manipulation of plants to improve productivity. Dr. J.S.