Swallowtail butterflies, a major family of insects, are threatened with extinction around the world. In the Americas alone, 40 of the 143 species are on the critical list of the World Conservation Union. This meticulously prepared book was obviously a labor of love by Tyler, its primary author, and those who took up the challenge of completing it after his death. The first two-thirds of the book are organized thematically on subjects of general interest, including butterflies in nature and culture, ecology and behavior, population biology of adults, host plants, mimicry, biogeography, classification techniques, and diversity. Text is usually on the right-hand page, with tables, graphs, maps, and illustrations on the left-hand page. The text itself is delightful to read, the author having a deft command of the English language ("a very particular kind of leaf tissue must be chewed up by an intermediary food processor called a caterpillar"). At the same time it is highly technical, using scientific terminology that may stymie the casual reader ("Graphiine larvae have in the first instar bifurcate setae on the dorsum, and very rarely retain any setose tubercles in later instars"). The typeface of the text is of average size, but that in the charts, graphs, tables, and maps is small and often so crowded as to be difficult to decipher. Words included in the glossary at the back of the book are indicated by a superscript butterfly. Illustrations include both black-and-white and color photographs, electron microscope views, and drawings. Each chapter ends with a section of do-it-yourself exercises. The instructions are complete enough for the novice, but younger students may need guidance from a science teacher or experienced naturalist. The last third of the book gives a synopsis of American swallowtails, with 94 pages of colorplates. Plate data include scientific name, gender, area where found, and owner/collector of specimen. The bibliography is 10 double-columned pages. A gazetteer of locations mentioned in the book gives latitude and longitude. Also included is a summary of name changes for swallowtails. There is a systematic index to plants and animals and a separate subject index. The lay reader may be confounded by this work because of its scientific focus. This should not, however, deter those who enjoy reading popular science. The text is so well written that those who read authors such as Gould or Sagan will find this book fascinating, too. It may be too cumbersome to use for ready reference but will have a readership in academic libraries that support zoological and ecological programs and in high schools with AP science curricula. It will also make an excellent textbook.