This study is the first to provide direct observations of dyadic interactions with friends for preschool-aged disruptive children. Forty preschoolers (mean age 52 months) rated by parents as "hard to manage" on Goodman's (1997) Strengths and Difficulties Questionnaire (SDQ), as well as 40 control children (matched for age, gender, school, and ethnic background) were filmed for 20 minutes on two occasions playing with a teacher-nominated best friend. The videos were transcribed and coded for antisocial behaviour, displays of negative emotion, and empathic/prosocial responses to friend's distress. Individual differences in social behaviour were considered in relation to false-belief performance, affective perspective taking, and executive function skills (planning and inhibitory control). Compared with controls, the hard-to-manage group showed significantly higher rates of both antisocial behaviour and displays of negative emotion, as well as significantly lower rates of emphatic/prosocial responses. Across both groups combined, frequencies of angry and antisocial behaviours were related to poor executive control. Mental-state understanding was not significantly correlated with antisocial behaviour, emotion display, or empathy, suggesting that the interpersonal problems of young disruptive children owe more to failure of behavioural regulation than to problems in social understanding per se. However, given the relatively low power of the study, these findings require replication with a larger sample.