NKT cells comprise a distinct T cell subset that acquires effector function during development and prior to antigen exposure. NKT cells are of limited antigen specificity but possess the ability to be recruited into an immune response without the need for further differentiation or proliferation and thus may be considered to function as memory cells or as part of the innate immune system. Although the development and maturation of NKT cells share some similarities with conventional T cell populations, many transcriptional regulators and signaling molecules are known to be uniquely required for NKT cell development. Recently, new transcription factors that specify NKT lineage and effector function and novel roles for previously identified transcriptional regulators in the differentiation of the NKT cell population have been discovered.