This paper focuses on young men's views on the school sex education they have received, the influence of this sex education on their intended or actual behaviour, and the extent to which other sources of information complement or supplement school sex education. Thirty-five in-depth interviews and eight group discussions were conducted with male pupils from six schools in the east of Scotland. Most of those interviewed did cite school as a useful source in learning about sex. The most commonly named highlights were learning more about what girls think about sexual matters and learning how to use a condom. Nine described how something they had learned in school sex education had changed the way they had behaved in a sexual encounter. A further eight, who had not experienced sexual intercourse, talked about how they thought sex education would influence their behaviour in a positive way in the future. The most common criticism of sex education was that it was not explicit enough. Although friends and/or television were named by the majority of young men as useful, for most young men school sex education appeared to be the only substantive source of information they had received on sexual matters. (Contains 2 tables.)