The rapid adoption of new forms of digital communication is now attracting the attention of researchers from a wide range of disciplines in the social sciences. In the landscape of social media, the microblogging application Twitter has rapidly become an accepted feature of everyday life with a broad appeal. This paper, from a dual autoethnography (Davies and Merchant, 2007) over one year, is a reflexive account of the experience of two academic Twitter users. We offer analyses of the functionalities of the semiotic environment and trace how our meaning making practices illuminate Bakhtinian (1986) principles of human communication, while at the same time constituting literacies that are distinctively new in character. We show how communication using Web 2.0 technologies can be described as semiotic and sociolinguistic practice and offer an appropriately dialogic and exploratory methodology to the study of New Literacies. (Contains 6 figures and 1 table.)