Introduction: Young adulthood (ages 18-25) is a high-risk period for loneliness, particularly during educational transitions. Loneliness has negative consequences for mental health, physical health, and educational achievement. Psychologists conceptualize loneliness as emerging from a discrepancy between expected and experienced social connection, but this has been under-explored during young adulthood. Method: Drawing on thematic analysis of eight focus groups with 21 young adults in the UK, this paper explores the differences between retrospective expectations and experience of social connection during the transition into university and the implications for loneliness. Results: Whilst social expectations, experiences, and preferences vary considerably, young adults' perception of whether expectations are met is ostensibly more consequential for understanding social (dis)satisfaction than objective indicators of the social experience, such as number or quality of friendships. Moreover, discrepancies between social expectations and experience are intensified by a widespread presumption that social relationships in adulthood will form and function as they did at school, resulting in unexpected barriers, challenges, and effort involved in friendship formation. Conclusions: The findings affirm the importance of addressing loneliness holistically during points of transition and creating socially supportive communities for young adults, particularly at university.