Though no celebrity book club has reached the heights in terms of driving sales that Oprah Winfrey’s club did during its heyday, book clubs started by a number of well-known readers do give sales a boost. One of the most effective has been Reese’s Book Club, started by actor and producer Reese Witherspoon. The club was born out of Witherspoon’s Instagram account, where she posted photos of books she read.

When Hello Sunshine, the media company started by Witherspoon and Seth Rodsky, was being formed, Witherspoon decided to create a Reese’s Book Club Instagram account to spotlight titles that bring women’s stories forward, according to Sarah Harden, CEO of Hello Sunshine. Now, Witherspoon picks one book each month, posts it to the @reesesbookclub account (which has 1.3 million followers), and promotes the title for that month.

Witherspoon’s selections have been varied, ranging from new titles to backlist, by authors both new and established. That variety is something appreciated by Carolyn Reidy, CEO of Simon & Schuster. Speaking about celebrity book clubs in general, Reidy said the clubs have been particularly valuable because they often highlight books that aren’t bestsellers.

That is certainly true of Reese’s Book Club, and while a Witherspoon selection doesn’t necessarily mean a title will become an immediate bestseller, it does mean a jump in sales, and a selection often provides a spark that can drive future sales. For example, The Proposal by Jasmine Guillory was published in October 2018 and sold almost 3,100 copies in its first week, according to NPD BookScan. Sales had cooled to about 2,900 copies the week before The Proposal’s selection by Witherspoon in February, after which sales jumped to almost 7,700 print copies. The book was steadily selling more than 1,000 copies per week into August, and the novel has now sold 82,000 copies.

Perhaps Witherspoon’s most famous pick is Where the Crawdads Sing by debut author Delia Owens. That novel, published in August 2018, was a Reese’s Book Club selection in September 2018, and the pick, accompanied by strong word of mouth, propelled Crawdads to become the most popular novel in several years, selling nearly two million print copies since its release.

According to Harden, Witherspoon has no plans to end the club anytime soon. “We are just getting started,” she says. “In 2020, expect to see us doing more in real life with our community and building out what it means to be a member of this magical circle of book lovers.”