We communicate by means of language and actions, which we represent in our cognitive system (i.e., action representations). Communication is successful if interaction partners understand each other. This doctoral thesis studies the contribution of the mirror neuron system to the processing of communicative signals in early language development. Two studies investigated if and how the mirror neuron system processes communicative signals (i.e., actions and language) in 18-24-month-olds. Both studies assessed the activity of the mirror neuron system (MNS) by electroencephalography (EEG). Study 1 showed that the mirror neuron system is involved in processing action-related language, specifically action verbs. To do so, it takes the role of a prediction system, which was demonstrated by Study 2, in which action prediction was enhanced if corresponding linguistic information was present previously. In conclusion, the findings of this doctoral thesis point to an involvement of the mirror neuron system in processing communicative signals early in language development by making predictions. Furthermore, it was shown that action and language are interrelated.