This is a very good book, everyone should be well educated on sex, by reading books from people like Masters and Johnson. They are serious professionals on the issue, with countless researches. And as doctors we can rely on them. This book is written for all ages, since childhood to people over 45 years old. The sex life of my partner and I, changed incredibly. We are 58yo and 54 and we have been together for 9 months. As latinamericans had a lot of troubles with our sex life. But this book it is not important only for people like us. Every parent should read it and learn how to educate his (her) kids. every adolescent should read it too and learn how to avoid pregnancies in early stages of life.