‘The virtual is opposed not to the real but to the actual’. (Deleuze Citation1994, 208) As this quote reminds us, virtual possibilities and worlds are real. As a limited actual articulation of the virtual, experiences in online virtual worlds constitute substantive components of the assemblage of subjectivity for the people about whom we write. Virtual worlds also provide possibilities for the actualization of ranges of experiences that are not possible outside forums such as Second Life.Footnote1 In exploring the ‘realness’ of virtual worlds, we advance a particular theoretical inquiry into processes of achieving social sustainability in Second Life. We give a summary of sustainable practice for web design and note the implications of the lack of discussion of sustainable practice in relation to 3D virtual worlds. We then move into virtual worlds and undertake three case studies of cultures working towards being sustainable in Second Life. We take up a Deleuzian ontology as a means of thinking about sustaining cultures and valuing differenciation. After Deleuze (Citation1994), we take differenciation to mean the material process by which something becomes different from itself. Deleuze draws a distinction between this material change and the virtual process of an ‘Idea’ changing or becoming different from itself, which he calls ‘differentiation’. Specifically, he states: We call the determination of the virtual content of an Idea differentiation; we call the actualisation of that virtuality into species and distinguished parts differenciation. It is always in relation to a differentiated problem or to the differentiated conditions of a problem that a differenciation of species and parts is carried out, as though it corresponded to the cases of solution of the problem. (Deleuze Citation1994, 207) Differenciation is the realization of virtual possibilities. It is also a fundamental aspect of Deleuze, and Deleuze and Guattari's productive concept of desire, which is ontological. Matter is the expression(s) of desire. Through this generative notion of desire, Deleuze and Guattari (Citation1983), mount a challenge to Freudian psychoanalysis and its tendency to ‘overcode’ desire. They argue that by channelling desire back into the family and limiting revolutionary desire, psychoanalysis operates in the service of capitalism. As an alternative, Deleuze and Guattari developed the concept of schizoanalysis,Footnote2 which enables an understanding of assemblages and an associated focus on context. Developing strategies to counter, or question, the impact of capitalism on social relations is an ongoing challenge. We explore such challenges through our case studies. These three communities operate in productive tension with capitalism. They rely on the capitalist corporation Linden Labs for their existence, yet they are not economically sustainable in capitalist terms. They survive through an assortment of changing entrepreneurial practices, which celebrate, and some of which commodify, difference. In enquiring into the sustainable nature of such cultures, we begin with a contextual overview of sustainable practice for web design and note the lack of such discussion in relation to 3D virtual worlds.