to a . a large majority [of the teenagers] had intercourse prior to seeking contraception at the family planning clinic .... most [were] either misinformed or uninformed about the various methods of contraception.... a single, informal rap session ... improved knowledge substantially in most areas.' What do teenagers know about contraception, abortion, venereal disease and the reproductive system? Can education improve their knowledge significantly? With evidence that more than two million unmarried women aged 15-19 are sexually active and at risk of an unintended pregnancy;' that approximately one-third of the legal abortions in the United States are performed on women under 20 years of age; 2 and that venereal disease among teenagers is pandemic, with the number of reported cases almost quadrupling between 1960 and 1972,3 these questions are far from academic. Many teenagers recognize the hazards associated with unprotected coitus, as is demonstrated by the fact that substantial numbers are turning to family planning clinics for contraceptive services; in 1973, nearly three in 10 of the 3.2 million patients seen in organized family planning programs were teenagers.4 At some centers, teenagers are seen along with adults in the regular clinic sessions. At others, special programs for teens have been established and, in these, education is an important component of the program .5 Typical of the latter approach is the teen service of the Planned Parenthood League of Detroit. Its Youth Education on Sex Teen Center (YES) provides nonprescription contraception for teenage men and women, prescription contraception and related medical services for women under the age of 18, and sex education for adolescents of both sexes (the latter, a prerequisite for medical contraceptive services). In an effort to provide data necessary for sex education program implementation, a two-part study was undertaken by the authors, with the cooperation of the Planned Parenthood League, to explore teen knowledge of contraception, abortion, reproduction and venereal disease, and to ascertain whether education in these specific areas results in improved knowledge. Confirming the experience of others who work with teenagers,6 the study revealed that a large majority had intercourse prior to seeking contraception at the family planning clinic. The study also showed that most are either misinformed or uninformed about the various methods of contraception; that most obtain their information (and misinformation) from their peers or the mass media, with parents, educators and health professionals contributing only minimally; and that most are well-informed about abortion and venereal disease. Education, in the form of a single, informal rap session led by young professionals attuned to the psychosexual concerns of the teenagers, improved knowledge substantially in most areas. Study Design