There is a distinct lack of knowledge about how the rise of private security relates to young people in adversarial encounters. Prior studies suggest that the policing of young people by police is a common occurrence and social biases exist. However, policing of young people by private security guards has gained much less attention. Drawing on a large-scale youth survey (N = 5826), this article examines the extent and social biases of adversarial contacts between private security guards and youths. The findings showed that 29% of 15- to 16-year-old Finnish youths reported adversarial security guard contact in a year. The open-ended responses indicated that young people were typically suspected of shoplifting, being a nuisance or drinking alcohol. Social biases were examined using the differential selection hypothesis, which suggests that some groups are disproportionately targeted. Multivariate analysis showed that, as expected, delinquency and alcohol use were associated with adversarial contacts. Howeve...