Mario Pei is Professor of Romance Philology at Columbia University. His scholarly book, The Families of Words, is actually a dictionary of Indo-European etymologies in the English language, although the book is not arranged as a dictionary. The 'families' in question are, of course, groups of etymologically related words: the 'family tree' is traced through various languages back to an original root in an assumed primitive Indo-European language. These trees or etymological charts appear throughout the text: indeed, the text must be read as footnotes to the charts. The publishers promise full indices in the back with separate sections for each language (English, French, Welsh, etc.) so that the book can readily be used as an etymological dictionary. It is a little difficult to see why the book was not set up as a dictionary in the first place, since the present chapter divisions (on the basis of number of branches in the family tree) seem contrived. Hardly a book to read from front to back, but most interesting for those with an etymological curiosity. However, in several instances non-obvious jumps in meaning between related words were not explained or justified in the text.