Why does one ad succeed, while another fails? This classic by a veteran copywriter analyzes hundreds of profitable ads, offering many side-by-side comparisons between similar but not equally effective ads. These analyses yield principles, procedures, tips, and practical suggestions — each tested with decades of experience — that can be immediately applied to every medium and style of advertising. During his six-decade career at the top advertising firm of BBDO (Batten, Barton, Durstine & Osborn), author John Caples pioneered the techniques of effective copy-testing. All copywriters, from cub to chief, can benefit from his helpful suggestions. "This is a valuable textbook for every student of advertising and every writer of ads," declared the Christian Science Monitor, and Booklist pronounced it "of interest to anyone interested in what makes our business economy work."