First sexual intercourse is an event of immense social and personal significance, which also has major health implications. However, there has been no recent review of the literature in the United Kingdom specifically relating to this event. This review addresses this gap, examining the timing, circumstances, and consequences of first heterosexual intercourse. Studies were identified by electronic search, as well as through contact with experts in the field. Academic literature published from 1960 and pertaining to the UK context was included. A dominant focus of the literature is on the timing of the event, which shows that the age at which young people become sexually active has fallen in recent decades. In addition, much of the literature is concerned with the risk of adverse outcomes, and a young age at first sex is often associated with more negative consequences. There is evidence to suggest that age may not be the most useful criterion for judging optimal timing for first having sex. It is proposed that a more promising concept in relation to first sexual intercourse is that of sexual readiness.