Recent studies have shown that the transcriptional regulator promyelocytic leukemia zinc finger (PLZF) controls the development of essentially all of the innate-like features of invariant Natural Killer T (NKT) cells. For example, PLZF-deficient NKT cells do not acquire an ‘activated’ phenotype nor do they acquire the capacity to secrete multiple cytokines upon primary stimulation. The function of a subset of γδ T cells has now also been shown to be dependent upon expression of PLZF. Furthermore, IL-4 produced by PLZF-expressing cells causes some CD8 T cells to acquire innate-like features. Therefore, it is becoming clear that PLZF has a broad impact on the immune response. Here we discuss the current understanding of how expression of PLZF, the innate T cell determinant, is initiated during T cell development.