Everything You Always Wanted to Know About Sex* (*But Were Afraid to Ask) is a book (1969, updated 1999) by U.S. physician David Reuben. It was one of the first sex manuals that entered mainstream culture in the 1960s, and it had a profound effect on sex education and in liberalizing attitudes towards sex. It was the most popular non-fiction book of its era and became part of the Sexual Revolution of modern America.
The book was No. 1 best-seller in 51 countries and reached more than 100 million readers. In 1972 it was parodied by Woody Allen in the comedy filmof the same name and received a favorable response from movie critics.