A review of the most important areas of the biochemistry of herbicide action. The introductory chapter begins with the field of herbicide discovery, followed by chapters dealing with the herbicidal inhibition of photosynthesis, carotenoid biosynthesis, lipid biosynthesis, and amino acid biosynthesis. The metabolism of herbicides is discussed with particular reference to the formation of toxic components from non-toxic chemicals, and also the inactivation of toxic chemicals as a basis for selectivity. The final chapters are concerned with mechanisms of herbicide resistance in plants and the possibility of transferring resistance to susceptible crops. A glossary of the most important herbicidal chemicals mentioned in the text is included.