Theory of mind (ToM) undergoes significant developments during childhood, particularly between the ages of four and seven years. A growing body of research has indicated that children’s social understanding may be related to their social behaviour with peers, in line with Theory Theory which proposes that children’s social cognition is influenced by and influences their peer interactions. The current study examined the relationship between ToM and behaviour among 193 children aged 4–7 years. Children carried out a battery of ToM tasks, and teaching staff reported on children’s aggressive, prosocial, and solitary behaviour and victimisation experiences. Aggression was not directly related to ToM; prosocial behaviour was positively associated with ToM for girls but not boys. Solitary behaviour and victimisation were negatively related to ToM. When this was broken down by gender, there was only a significant association between solitary behaviour and ToM for boys. When controlling for the relationship between behaviours, the only significant predictor of ToM was solitary behaviour for boys. ToM was also a significant predictor of solitary behaviour for boys, demonstrating that there is a bidirectional relationship at play. The findings highlight the importance of looking across these four behaviour types and understanding the relationship between behaviour profiles and ToM for boys and girls separately.