For decades in this country, people concerned about adolescent sexual behavior, pregnancy, and sexually transmitted disease, including HIV, have striven to increase parent-child communication about sexuality. Their efforts were frequently based upon several beliefs: parents should be and are the primary sexuality educators of their children; parents have considerable difficulty talking with their own children about sexuality (and vice versa) and do so infrequently and inadequately; increasing effective parent-child communication about sexuality will lead to less sexual risk taking on the part of teenagers; and properly designed programs can increase effective parent-child communication about sexuality, can increase comfort with that communication, and can thereby reduce adolescent sexual risk taking.In addition, encouraging parents to be the primary sexuality educators of their children has been acceptable politically. For example, it is far less controversial to help parents communicate their own values to their own children, and hopefully to thereby decrease sexual risk-taking behavior, than to provide abstinence-only education, to teach sex or HIV education that discusses condoms and other forms of contraception, or to provide condoms or contraceptives through public institutions such as schools.This chapter describes different approaches that people have used to increase parent-child communication about sexuality and summarizes studies that have measured their impact. It focuses primarily on the impact of programs on parent-child communication, but it also summarizes the limited research on the impact of such programs on adolescent sexual behavior, or on other determinants of that behavior.