In the past decade or so, the universal dominance of l- over d-amino acids in living organisms has been questioned. This interesting and wide-ranging book summarizes the current state of knowledge on the occurrence, biosynthesis, and roles of d-amino acid containing peptides, with a strong emphasis on those in multicellular organisms. The opening chapter by Scaloni et al. provides a practical guide to the detection and analysis of d-amino acids. The subsequent four chapters describe studies related to the presence of d-amino acids in antimicrobial and opioid peptides in frogs, molluscan neuropeptides, and crustacean hyperglycemic hormones. Although the work could have been summarized more succinctly and there is, as is common with this type of text, some overlap between the chapters, the inclusion of experimental details will be of interest to the specialist.