Gilles Deleuze was a major figure in Continental Philosophy of the late twentieth century and is pivotal to the adoption of Poststructuralism in the social sciences. Deleuze’s philosophy and relevance to Critical Social Psychology is not easily summarised because it is not singular and narrowly systematic, but rather plural, open and creative. Two major themes in his work are particularly valuable to psychology—his treatment of thought and sensemaking and his concern with being and becoming. In this chapter we show how these two themes combine in a number of distinct topics. Deleuze describes two kinds of multiplicity, quantitative and qualitative, and how experience is constituted through indivisible flows rather than clearly defined intervals and parts. His key concepts of virtual and actual provide a way to reformulate questions around realism and relativism, and to demonstrate that that the ideal is not abstract, but rather in the process of being determined through our actions. Deleuze approaches subjectivity as a continuously transforming and plural style of living rather than a self-contained ‘thing’. Affect is similarly treated in terms of what can be done within an assemblage and the relations we are capable of forming. Critical Social Psychologists will find in Deleuze’s work a rich series of resource to inform an experimental and transformative approach to theoretical and empirical work.