In conversation, speakers and listeners coordinate both their behavior and their mental states. Multi-brain studies, which record and relate to each other the neural activity of two or more brains, can provide insights into a coordination of neural states between communicating individuals. In this chapter we review recent multi-brain studies using functional magnetic resonance imaging (fMRI) or electroencephalography (EEG) to investigate verbal and non-verbal communication. We summarize common findings with respect to spatial and temporal aspects of inter-brain coordination. We then critically discuss challenges arising from studying dialogue in ecologically valid, yet experimentally controlled neuroscientific settings. We conclude by providing an outlook of how technical and methodological advances may enable future multi-brain studies to better address these challenges.