The majority of T lymphocytes, sometimes referred to as as mainstream or conventional T cells, are characterized by a diverse T cell antigen receptor (TCR) repertoire. They require antigen priming in order to become memory cells capable of mounting a rapid effector response. It has become established, however, that there are several distinct T cell lineages that exhibit a memory phenotype in the absence of antigen priming, even as they differentiate in the thymus. These lymphocytes typically express a markedly restricted TCR repertoire and their rapid response kinetics has led to their being described as innate-like T cells. In addition, several of these subsets typically express surface markers commonly found on natural killer cells, which has led to the moniker natural killer T cells (NKT cells). This review will describe our current understanding of the unique ways whereby transcription factors control the development and function of an abundant and widely studied lineage of NKT cells that recognizes glycolipid antigens.