The increase of undesired pregnancies as well as sexually transmitted diseases among teenagers is a serious problem which is alarmingly preoccupying. More than ever is it necessary to identify it's underlying causes in order to conteract its devastating consequences. The latter has inspired the following study which main purpose is to give an overview about several interesting questions for health promotion among teenagers. The results of this research show the knowledge, attitudes and teenagers” sexual behaviours as well as giving information about the causes which determine the efficiency in how these use contraceptive methods. Such study was undertaken by the Department of Developmental and Educational Psychology of the University of Seville upon a cooperation agreement with the Andalusian Health Service.