Fifteen years after Amber-Allen Publishing released don Miguel Ruiz’s bestseller The Four Agreements, the book climbed to the number one spot on Amazon and Barnes & Noble’s after the author was the featured guest on Oprah Winfrey’s TV show Super Soul Sunday on March 3 and 10.

“We blew 45,000 copies of don Miguel’s book out of our warehouse after Oprah interviewed him last month,” says Janet Mills, publisher of Amber-Allen, who approached the producer of Super Soul Sunday last year about having her author on the show with the 15th anniversary edition of The Four Agreements. Super Soul Sunday first aired on the OWN Network in October 2011 and explores themes including spirituality and personal self-fulfillment and has featured guests such as Elie Wiesel, Wayne Dyer, and Thich Nhat Hanh. “Super Soul Sunday is the broadcast home for Oprah’s Book Club 2.0, which is the digital reincarnation of Oprah’s Book Club,” says Leah Sparkes Ampuero, senior publicity manager, communications, for Harpo Studios.

The Four Agreements has sold 5.2 million copies in the U.S. and has been translated into 38 languages. “The book has endured because there is a simple truth to don Miguel’s words, a timeless wisdom that readers can feel instantly,” says Mills. “Strong word-of-mouth marketing is one of the most effective ways to sell books; people tend to trust a personal recommendation over an advertisement, and this has been the case with The Four Agreements.” Amber-Allen is planning to actively brand the book in the future, including the development of a core curriculum for use in rehab centers. Mills is also working on a children’s edition of the book with an accompanying teacher’s guide for classroom use. In addition, there is talk of a film based on The Four Agreements.

“The incredible success of The Four Agreements owes a big debt of gratitude to Oprah's endorsement,” says Mills. Winfrey featured the book on her show in 2000, 2001, and again on Super Soul Sunday. “Sales have sky-rocketed each time.” Mills founded Amber-Allen in 1990, and the press has about 50 titles in print; the company publishes one or two books a year. Some, such as the 1994 bestseller The Seven Spiritual Laws of Success by Deepak Chopra, are co-published with New World Library.