There is a difference between theory and theorizing. One way or another, theory is central to the organization of most academic disciplines: for example, as a framework of concepts that expresses preoccupations, that codifies linkages, that relates discoveries, that raises questions. But theorizing is the becoming of theory: for example, running into problems, feeling perplexity, creating space, forming concepts, finding time, condensing frameworks, forcing conclusions – a living reality that is (for reasons explored below) neglected as a topic of inquiry. I address this deficiency here by engaging with theorizing as a legitimate, perhaps inescapable theme, albeit one that remains elusive and that must as far as possible be grasped directly as it occurs. In developing this engagement, I suggest that the philosophy of Deleuze and Guattari offers an appropriate point of departure and – through a reading of Difference and Repetition and What is Philosophy?, and through a synthesis of this with the experience of theorizing – I draw out the components of a Deleuzian theory of theorizing.