E protein transcription factors and their negative regulators the Id proteins have been implicated in many different aspects of invariant Natural Killer T (iNKT) cell biology. Previously, we have shown the E protein transcription factor, HEB, is essential for the earliest stages of iNKT cell thymic development and that the Id protein, Id2, is required for iNKT cell peripheral survival. Additionally, we have shown that E proteins positively regulate PLZF expression in iNKT cells during thymic development and that both Id2 and Id3 were required for differentiation of specific iNKT cell subsets. Our most recent data demonstrated that Id2 was required for regulating hyporesponsive iNKT cells indicating these transcriptional regulators can affect iNKT cell function as well as differentiation and survival. Here we present new preliminary data showing Id3 is highly expressed by a subset of iNKT cells in adipose tissue. Conditional loss of Id3 resulted in significant loss of activated adipose-resident iNKT cells, while loss of both Id2 and Id3 led to complete loss of adipose resident iNKT cells. We are currently exploring how E and Id proteins together regulate adipose resident iNKT cell differentiation and function.