Joint language production and the representation of other speakers' utterances.Joint language production is the study of the mechanisms involved in producing language jointly with another real or assumed speaker. Using relevant tasks, researchers have asked how (if at all) speakers represent one another's utterances (which we term co-representation) and specifically examined how such representations affect language production. They have compared the process of producing language jointly to the process of producing language individually, and have done so to address a question that is important for the study of both comprehension and production: How do language production processes relate to the representation of others' utterances? If production processes contribute to co-representation, then we would expect to find that co-representation affects actual language production. We use the term joint language production to refer both to cases where two people speak at the same time and to cases where people take turns speaking (e.g., A names a picture, then B names a picture). Furthermore, we include both situations where speakers are simply aware of each other's tasks (e.g., Gambi et al., 2015a;Kuhlen & Abdel Rahman, 2017) and situations where speakers intend to coordinate with each other, such as in choric production (Cummins, 2003(Cummins, , 2009Jasmin et al., 2016), or when they are instructed to jointly construct a meaningful sentence (e.g., Lelonkiewicz & Gambi, 2020) or to minimize the silent pause between their utterances (e.g., Hoedemaker & Meyer, 2018).Importantly, we use it to refer not only to situations where two people are actually producing, but also to instances when one participant produces while believing that another person is also producing (whether the participant receives any feedback about their partner's production or not, or even whether there is a real partner or not). Finally, speaking individually (the other side of the comparison) can refer either to one speaker performing just half of the joint production task (e.g., A names a picture, but then nobody speaks) or to one speaker performing the whole of the task (e.g., A names a picture, and then names another picture). Throughout the chapter, we specify exactly what is meant by "jointly" and "individually" with reference to particular studies, but we first explain the theoretical importance of this comparison and thus the unique contribution made by this literature.