Sexually active young adults are at an increased risk of acquiring sexually transmitted infections (STIs) or experiencing an unplanned pregnancy. Sexual behaviours such as inconsistent condom use, multiple partners and casual sex are known risk factors for negative sexual health outcomes. Sexually active higher education students are classified as a high-risk population in terms of sexual ill-health and are considered more likely to engage in risky sexual behaviours. Less is known about the sexual practices of the non-student young adult population. This study investigates and compares the sexual behaviour of 427 students and 280 non-students aged 19-22 years based on data from the Irish Study of Sexual Health and Relationships. No variation in attitudes and beliefs regarding sex was found between the two groups, neither was there a difference in STI diagnosis or use of sexual health services. Inconsistent condom use, early sexual initiation, high levels of sexual activity and greater instances of multiple partners were found among the non-student population. This highlights the need to distinguish between these young adult sub-groups and to expand understanding of the determinants of sexual health and behaviour among young people outside of tertiary education to enable more effective sexual health promotion.