Materiality in some form often becomes the basis for analytically distinguishing language from media for many theorists, even when these scholars disagree over the basic definitions. This chapter focuses on the materiality of the medium itself, aspects such as entextualization, participant structure, and remediation. By turning to materiality, one can begin to focus on some aspects of entextualization as a process in which the ways in which a text is a material form is integral to how a text can be separated from its context and integrated into other contexts. The chapter discusses analyses that result when one takes mediated communication to be the opposite of immediacy, when the central analytical dichotomy is between mediated communication and co-presence. It also focuses on materiality has the potential to transform who or what counts as a mediator, framing in unexpected ways the roles humans and non-humans might play in mediating communication.