Little is known about the role of affectionate behaviours — factors traditionally understood within the context of romantic relationships — in uncommitted ‘casual sex’ encounters. In a sample of U.S. undergraduate emerging adults aged 18–25 years (N = 639) we conducted a preliminary internet-based questionnaire investigation into the role of affectionate behaviours — operationalised here as cuddling, spending the night and cuddling, foreplay, and eye gazing — across two sexual relationship contexts: (committed) traditional romantic relationships and (uncommitted) casual sex encounters. While affectionate behaviours were desired more often in romantic relationships than in casual sexual encounters, many respondents (both men and women) engaged in these affectionate behaviours during casual sexual encounters as well. This was especially pronounced in those who expressed a preference for casual sex encounters over romantic relationships: in a casual sex context these participants were about 1.5 times as likely to cuddle, 1.5 times as likely to spend the night and cuddle, and nearly 5 times as likely to engage in foreplay with a partner. The current study emphasises the importance of considering relationship context in sexuality and relationship research, and the need for further theoretical and empirical research on dimensions of intimacy, including affection, in people's diverse romantic and sexual lives.