Finland is probably the only country where sex education has been studied in two consecutive national surveys, in 1996 and 2006 directed at biology and health education teachers, and in 2000 and 2006 by measuring adolescents' sexual knowledge. In 2006, responses from teachers and students could be combined for 339 schools. The most important educational objectives of sex education in the 2000s were, based on teachers' reports, to educate students to act responsibly and to provide them with the correct facts. Among boys, sex education had a much more important role in relation to their sexual knowledge than among girls. For girls, performing well in school was a more important predictor of a higher level of sexual knowledge than the number of hours allocated to sex education in school. The level of students' sexual knowledge was promoted positively by teachers who wanted to teach attitudes of naturalness and tolerance toward sexuality, found sexual issues easy to talk about, told students of their own personal life, and used classroom techniques including drama and role-play methods and presentations, and lectures given by students themselves. In sum, Finland represents an advanced model of comprehensive sex education in Europe. (Contains 4 tables and 1 note.)