The editor of the Saturday Review gives a brief and readable study of best sellerdom. Question -- is the subject of interest outside the Trade? Possibly for study groups, etc. Stevens discusses specific examples, specific motivating factors, from advertising to book club selection, from Woollcott's recommendations on the radio to timeliness. The conclusion is that no one thing makes a book click; that one thing or another makes a contribution. The right book -- at the right time -- and it will go. Figures and examples substantiate the whole. Popularly written.