This thesis examined the presentation of self in Massively Multiplayer Online games, to investigate how players create and maintain versions of self in these environments. Key research questions concerned the motivation for engaging in these behaviours, the impact of such activities on their offline lives and for those that did not engage in the active presentation of self, why they did not do this. There were three studies in the thesis, employing a combination of qualitative and quantitative methods. The first study consisted of interviews (n=29), analysed using Grounded theory, and the second an online focus group (n=13 participants) explored using thematic analysis. These results were combined to create a theoretical model for the presentation of self in MMOs. Based on these concept statements a third study (n=408) was created, using an online questionnaire design. Results indicated that a five factor model was the most satisfactory means of explaining the presentation of self in MMOs – with Presentation of the Existing Self, Social Interaction, Gaming Aesthetics, Presenting Different Sides of the Self, and Emotional Impact as the salient factors. Virtual environments are rapidly emerging as a core element of human socialising, as evidenced by the growth of the games industry and the expansion of social networking sites in the last ten years. MMOs represent just one type of virtual environment but also some of the most exciting, since they allow the presentation of multiple versions of self in a fantastical social environment. The thesis adds to the literature through its examination of the presentation of self, in illustrating how and why playe3rs experience and represent their offline self in MMOs. This has not been achieved in any other previously published work and is an original contribution to the literature.