This paper develops a theory of transgressive learning (t-learning) as it was experimented with in the International Science Council t-learning network. The method applied is a diffractive reading of conceptions of transgression in academic publications emerging from different cases. The results show that there can be no definite conduct to or understanding of transgression, as transgression itself entails a subversion of rules, contexts, and borders. Instead, the results document several overarching categorical positions and axiomatic understandings of transgression that emerge from the background of context-specific wicked sustainability issues. Transgressive learning can be understood as a set of contextually diverse techniques and practices that attempt to bring about change through and in learning. Transgressive learning can result in experiential learning excesses where the excess is the very source of difference and makes change possible. The diversity of conceptions of transgressive learning open up new entry points for engaging with sustainability-oriented learning and education that is open to change rather than to reproducing unsustainable social structures and dynamics.