Background: In first-episode psychosis, the family is considered an important part in the recovery process. This is often accompanied by significant distress, which is acknowledged in numerous studies. However, little is known about the psychological factors involved. Method: One hundred and twenty-seven caregivers of persons with first-episode psychosis completed a series of questionnaires aimed at investigating the contribution of expressed emotion and metacognitions to caregiver distress. Results: Linear mixed model analysis found that emotional over-involvement and metacognitions independently predicted caregiver distress. Mediation analysis using bootstrapping showed that emotional over-involvement could be seen as mediating the effect of metacognitions on distress. Conclusion: The current study is a first step towards understanding the role of metacognitions in caregiver distress, thus opening up for the possibility of using interventions from 'contextual behaviour therapies'. Implications and future studies are discussed.