On the premise that people achieve knowledge of things by sharing mental resources, what are the scope and philosophical significance of acts of shared intentionality in social discourse? Some philosophers and scientists of social cognition, most notably Jane Heal and Michael Tomasello, have drawn upon insights about the capacity of individual people to share mental resources and contents to argue for the importance of sociality in shaping mental activity. In this paper, I synthetize these strands of research with the aim (...) of comparing different claims about shared intentionality, and facilitate an assessment in the debate on the social aspects of self and mentality. (shrink)