The main goal of this book, The Structure and Confirmation of Evolutionary Theory (Lloyd 1988), “is to introduce, develop, and demonstrate the usefulness of a precise analysis of the structure of evolutionary theory” (p. 23), an analysis that treats evolutionary theory as built up out of complexly interrelated mathematical models. The book has a second goal as well, namely, “to offer … evidence of the appropriateness and utility of the semantic view of scientific theories” (ibid.). The appropriate audience for the book is not obvious. It is well suited for graduate courses in philosophy of biology, though it demands substantial knowledge of both disciplines. Lloyd has attempted to make it accessible to wider biological and philosophical audiences by minimizing the technical treatment of mathematical models, but I doubt that she has succeeded in making the book accessible to those unfamiliar with the models of population genetics or to biologists previously unversed in the philosophy of science.