Premature sexual activity of the young, before reaching physical and psycho-social maturity, brings along the risk of jeopardizing their reproductive health, mostly because it can lead to sexually transmitted infections or pregnancy, which is mostly unwanted in adolescence. The starting assumption of the promotion of reproductive health of the young is understanding and acceptance of their sexuality and relevant needs in social environment in which they live. Primarily in the family, the media, healthcare institutions and school. During the period of childhood and youth, school possesses the unique possibility to enable a large number of young people to acquire knowledge and skills related to sexuality and reproductive health and shape their values, attitudes and beliefs. The complexity of the process of making the decision about becoming sexually active, as well as the space for action towards its postponement to older age, are also indicated by the results of the research conducted in Belgrade, on the sample of one hundred and eleven female adolescents aged fourteen to twenty, who became sexually active at the age sixteen and earlier. These are primarily those results which refer to the meaning of love and sex in their value system, motives, feelings and attitudes related to becoming sexually active.