Prior research has shown that dealing with children with behaviour problems can generate feelings of helplessness and incompetence in teachers (Gray et al., 1996). This study aimed to investigate the relationship between educators' sense of self-efficacy and their perceptions of severity of hyperactive behaviour in boys and girls. Two questionnaires were used, composed by a vignette describing either an imaginary hyperactive boy or girl, followed by ratings of severity of the behaviour presented, the 'Emotional Reactions to Challenging Behaviours Scales' (Mitchell & Hastings, 1998) and the 'Difficult Behaviour Self-Efficacy Scale' (Hastings & Brown, 2002). The sample consisted of 115 Greek prospective nursery teachers. It was found that prospective educators feel significantly less competent to deal with hyperactive boys than girls, even when they present similar behaviour patterns. Their sense of self-efficacy was the best predictor for perceptions of severity of male hyperactive behaviour (β=-.34, p<.01), whereas their feelings of sadness were the best predictor for perceptions of severity of female hyperactive behaviour (β=-.29, p<.05). On the basis of these findings, we discuss the relationship between educators' sense of self-efficacy toward male and female hyperactivity and the meaning assigned to this behaviour. Possible implications for discipline practices and referral to Child Mental Health Services are discussed as well.