Michael Castleman is the author of 19 books, most recently “The Untold Story of Books: A Writer’s History of Book Publishing“, a passion project that represents a departure from his 45-year career writing about health and sexuality.

Speaking of sex, 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. In January 2021, his latest book, Sizzling Sex for Life, was published. His two previous sexualitacy guides—Sexual Solutions (1980) and Great Sex (2004)—have sold more than 600,000 copies. He also writes a free, weekly sex-related blog on Substack.

He 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 websites, magazines, and call-in radio shows.

From 1973 to 1978, he 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, he wrote more than 1,500 health articles for newspapers, magazines, and Web sites 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, he retired from health journalism but has continued to write about sexuality. Why? “The thank-you notes. 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.

Click here to contact Michael (no sex questions, please).

About Great Sex Guidance

Based on his more than 40 years of work,  he created Great Sex Guidance to be an authoritative, research-based, sex-information, and counseling resource for people of all ages and erotic dispositions. 

Here’s what some site visitors and sex experts say about GreatSexGuidance:

“This is what sex education should look like. GreatSexGuidance.com is a wonderful resource for people of all ages. The information is accurate, up-to-date, and written in an engaging style that should help lovers at every stage of life.” —Sex therapist Marty Klein, Ph.D., publisher of the SexualIntelligence newsletter.

“Thank you for answering me in such great detail. My boyfriend is also very impressed. Great advice. Thank you again, Michael.”—J.B., Tom’s River, New Jersey

“I had premature ejaculation for YEARS, and you cured me in a month. Thank you so much!”L.K., Vienna, Austria

“For authoritative advice about sex after 40, 50, 60 and beyond, look no further than Michael Castleman’s site. He can answer ALL your questions.” —Lybi Ma, editor, PsychologyToday.com.

“A major desire difference threatened my marriage. Then I found your article. Scheduling sex has really helped. I can’t thank you enough.”M.W, Ft.Lauderdale, FL

“Finally, my husband and I are having the sex we always dreamed of.”P.F., Des Moines, Iowa

“GreatSexGuidance provides reliable, practical information for making the most of sex at any age. I’ve always respected Castleman’s knowledgeable, compassionate sexuality books, and he’s brought the same sensibility to his site.”—Joan Price, author, Better Than I Ever Expected: Straight Talk About Sex After Sixty.

“I’m a nurse/social worker. So much great information here. Thank you! Such a gift!”A.N., Sydney, Australia

“Premature ejaculation has been driving my husband crazy since we were dating. We used your program, and after two months, he’s cured and so happy. Thank you from the bottom of my heart.”F.R., Dallas, TX

“Hey Michael, just wanted to thank you for your article on penis size. I’ve spent years beating myself up about being average. Then I read your article. You put me at ease about it all. So thank you for an informative article based on truth—not on what we see in porn. Much appreciated.”K.S., Santa Clara, CA

You can always write him at:

Post Office Box 9709

San Rafael, CA 94912



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