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• Intestinal IEL are a heterogeneous lymphocyte population. • In adult animals, the majority of CD8αα IEL precursors are self-reactive thymocytes that undergo agonist selection. • Alternative, and likely functionally distinct, precursors exist. The intestinal epithelium is the outermost cellular layer that separates the body from the gut lumen. The integrity of this protective mucosal barrier is crucial and maintained by specialized cells—intraepithelial lymphocytes (IEL). Much research has been conducted on these cells and our overall understanding of them is increasing rapidly. In this review we focus on the TCRαβ+ subset of CD8αα IEL. We discuss recent studies that shed light on the development, ontogeny, maintenance, and functional characteristics of CD8αα IEL, and highlight yet unanswered questions for future studies. [ABSTRACT FROM AUTHOR]