This chapter reviews studies which focus on Internet users’ attempts to change (challenge, reinforce, negotiate) current or past, stereotypical, individual and/or group identities in interactions. It thereby acknowledges that the literature regularly draws on various theoretical conceptions of identity. Perspectives on identity range from sociolinguistic understandings of the impact of social variables on linguistic variation to constructivist and discursive negotiations of identity as employed in conversation analysis, discourse analysis and discursive psychology. The latter ones share a particular view of identity as a complex, emergent, context-sensitive, social, ephemeral/changing and negotiable concept. Methodologies vary according to theoretical orientation so that we find a rich mixture of quantitative and qualitative studies. In addition to addressing these different conceptualisations of and approaches to identity, the chapter also reviews a number of key themes which emerge in the literature review: the importance of (im)politeness; the impact and negotiation of gender; the construction of expertise, authenticity and trust; the surfacing of emotions; the creation of in- and out-groups and community building; and the intertwining of offline and online acts of positioning.