A characteristic of mucosal-associated invariant T (MAIT) cells is the expression of TRAV1-2+ T cell re- ceptors (TCRs) that are activated by riboflavin metab- olite-based antigens (Ag) presented by the MHC-I related molecule, MR1. Whether the MR1-restricted T cell repertoire and associated Ag responsiveness extends beyond these cells remains unclear. Here, we describe MR1 autoreactivity and folate-derivative reactivity in a discrete subset of TRAV1-2+ MAIT cells. This recognition was attributable to CDR3b loop-mediated effects within a consensus TRAV1-2+ TCR-MR1-Ag footprint. Furthermore, we have demonstrated differential folate- and riboflavin-deriv- ative reactivity by a diverse population of ‘‘atypical’’ TRAV1-2� MR1-restricted T cells. We have shown that TRAV1-2� T cells are phenotypically heteroge- neous and largely distinct from TRAV1-2+ MAIT cells. A TRAV1-2� TCR docks more centrally on MR1, thereby adopting a markedly different molecular footprint to the TRAV1-2+ TCR. Accordingly, diversity within the MR1-restricted T cell repertoire leads to differing MR1-restricted Ag specificity.