Michael Castleman is the world’s most popular sexuality writer. His twice-monthly blog on PsychologyToday.com, All About Sex” launched in 2009, has amassed more than 50 million views. The free Question & Answer site he has published since 2010, GreatSexGuidance.com, has attracted 2 million more. His two previous sexualitacy guides—Sexual Solutions (1980) and Great Sex (2004)—have sold more than 600,000 copies.

Castleman has answered more than 12,000 sex questions from people around the world of all ages and sexual inclinations. In addition to his Question & Answer site, he spent 10 years (1997-2007) answering sex questions from customers of Xandria, then a major sex toy marketer, and five years (1991-1995) answering the sex questions submitted to Playboy’s “Advisor” column. He has also answered questions for WebMD and several other Web sites, magazines, and call-in radio shows.

From 1973 to 1978, Castleman wrote health articles for the alternative press. He defined health broadly: optimal wellness, illness prevention, mainstream medicine, alternative therapies, nutrition, fitness, and sexuality.

In 1978, he earned a Masters degree in Journalism from UC Berkeley. From 1979-2007, Castleman wrote more than 1,500 health articles for newspapers, magazines and websites about all of the above, including: the New York Times, WebMD, Salon.com, PlanetRx.com, AARP, Reader’s Digest, Smithsonian, Cosmopolitan, Redbook, Self, Family Circle, Ladies’ Home Journal, Prevention, Men’s Health, Men’s Fitness, Men’s Journal, Natural Health, Mother Jones, and The Nation. Library Journal called him “one of the nation’s leading health writers.”

In 2007, Castleman retired from health journalism but has continued to write about sexuality. Why? “The thank-you notes,” he explains. “Readers appreciated my health writing, but I’ve gotten many more thank-you notes from answering sex questions and providing sexuality information and counseling.”

Castleman has published 18 books with total sales of 2.5 million copies. His top seller, with sales of more than 1 million copies in four editions, is The New Healing Herbs, a folklore-meets-science guide to the benefits (and possible hazards) of 135 widely used medicinal plants. Four of Castleman’s books are mystery novels set in San Francisco and featuring a journalist sleuth and the city’s rich history.

Castleman has been interviewed on dozens of television, and radio programs, among them: Today, Good Morning, America, Charlie Rose, and Phil Donahue. He has also been featured on many podcasts.

Castleman grew up in a Long Island suburb of New York City. He earned a BA in English from the University of Michigan and graduated Phi Beta Kappa (1972). He lives in San Francisco. 

You can read additional details about his background, education, and career on his Wikipedia page.