In 1937, Hill published the best-selling book Think and Grow Rich, which went on to become Hill's most well-known work. Unlike with his prior publications, Hill's new wife Rosa Lee Beeland contributed substantially to the authoring and editing of Think and Grow Rich. Hill's biographers would later say this book sold 20 million copies over 50 years, although Richard Lingeman, “Alice Payne Hackett's '70 Years of Best Sellers' suggests the figure was considerably lower.”

Think and Grow Rich was written in 1937 by Napoleon Hill, promoted as a personal development and self-improvement book. Hill writes that he was inspired by a suggestion from business magnate and later-philanthropist Andrew Carnegie. While the book's title and much of the text concerns increased income, the author insists that the philosophy taught in the book can help people succeed in any line of work, to do and be anything they can imagine. First published during the Great Depression, at the time of Hill's death in 1970, Think and Grow Rich had sold more than 20 million copies, and by 2015 over 100 million copies had been sold worldwide. It remains the biggest seller of Napoleon Hill's books. BusinessWeek magazine's Best-Seller List ranked it the sixth best-selling paperback business book 70 years after it was published. Think and Grow Rich is listed in John C. Maxwell's A Lifetime "Must Read" Books List.

The 13 "steps" listed in the book are:

1. Desire
2. Faith
3. Autosuggestion
4. Specialized Knowledge
5. Imagination
6. Organized Planning
7. Decision
8. Persistence
9. Power of the Master Mind
10. The Mystery of Sex Transmutation
11. The Subconscious Mind
12. The Brain
13. The Sixth Sense