Young children in immigrant families tend to face more challenges and can often call upon fewer resources than their native-born peers. This situation adversely affects their social–emotional development. In this study, the development of emotion knowledge of 576 immigrant and native-born German children, aged 3–6 years, was compared at three time points over a 12-month period by means of a latent growth curve analysis. Language abilities and behavioural self-regulation were examined as mediators of the relation between immigration background and emotion knowledge. The immigrant children showed less emotion knowledge than did their native-born peers at each point of measurement. These effects were partially mediated by their behavioural self-regulation and their language abilities. How behavioural self-regulation and language abilities affect the development of emotion knowledge and what this effect means for interventions are discussed. Statement of contribution What is already known on this subject? Emotion knowledge develops rapidly between the ages of three and six. Emotion knowledge develops similarly in different cultures. What does this study adds? This study compares the development of emotion knowledge between immigrant children and native-born children. It includes language skills as mediator on the development of emotion knowledge. It also includes behavioural self-regulation as mediator on the development of emotion knowledge.