Background: Empirical research about late sexual debut and its consequences is limited, and further research is needed. Objective: To explore how students who had not had intercourse by the age of 18 years differed in terms of sociodemographic factors, physical and psychological health, sexual behavior, and history of sexual abuse from those who had. Materials and methods: This is a cross-sectional survey involving 3,380 Swedish 18-year-olds. Descriptive analyses were used to investigate different types of sexual behavior. Ordinal data concerning alcohol consumption, self-esteem, sexual and physical abuse, parental relationships, sense of coherence, and health were analyzed, and multiple regression was carried out to identify the most important factors associated with no sexual debut. Results: Just under a quarter of the adolescents had not had oral, anal, or vaginal sex by the age of 18 years, and they comprised the index group. They were characterized by being more likely to have caring fathers, parents born outside Europe, lower pornography consumption, lower alcohol and tobacco consumption, less antisocial behavior, and above all lower sexual desire (sometimes, adjusted odds ratio [aOR] 3.8; never/seldom, aOR 13.3) and fewer experiences of sexual abuse (aOR 25.5). Family structure and culture matters when it comes to the age of sexual debut. Conclusion: Adolescents with no sexual debut at 18 years of age seemed to live a more stable and cautious life than more sexual experienced peers, exemplified by fewer antisocial acts, less smoking and alcohol/drug consumption, less sexual desire, and less experience of sexual abuse.