There is a lack of knowledge on which factors influence the effectiveness of sex education on the competence of boundary setting, while a high level of sexual competence is related to a healthy sexual development. Therefore, Qpido, an organisation that promotes sexual resilience, developed a sex education program called “Love is…”. This program aims at increasing the sexual competence, knowledge, positive attitudes and perceiving positive social norms of adolescents. Being competent in setting boundaries is in this research the main focus since this is related to a healthy sexual development. Therefore, the aim of the study is to evaluate and help improve sex education program “Love is…” by identifying the factors that influence the self-perceived competence of boundary setting for adolescents in secondary school on the long-term.