Both participation and argumentation (OECD, 2022) are important keywords in educational contexts. While participation is seen as a crucial prerequisite for education and collaborative learning in general, argumentation as a discursive practice serves to convey and negotiate--also school-specific--knowledge. This paper explores repetition in argumentative events as a technique of establishing--or even hindering--participation in terms of alignment and affiliation. It can serve as a strategy for participation by signalling responsiveness and thematic coherence--and thus inclusion. At the same time, however, studies show that repetition can also signal contradiction and rejection--and thus exclusion. So far, we know little about how exactly these functional differences are produced--especially in younger children. Therefore, the paper explores how children use repetition as a resource for negotiating participation in argumentative events. Using authentic data in the form of observations and transcriptions of audio and video recordings from child-child-interactions of 15 Hebrew- and 31 German-speaking children aged 3-6 years, we identify oral argumentative events and investigate different forms of repetitions and their respective relevance for enabling participation. Our results show that, on the one hand, minimal and partial repetitions are used by the children in an inclusive way, creating closeness between the participants. On the other hand, children use complete repetitions more as an excluding technique, displaying misalignment and disaffiliation, in order to challenge and mock each other. The findings suggest that this line of research has significant potential to provide new insights into the formation of social relationships between peers, into the prevention or establishment of participation, which itself is a prerequisite for joint learning, as well as insights into the acquisition of argumentative competence.