Endometrial carcinoma is the most common type of gynecologic malignancy and has shown a steady rise in incidence over recent decades. Formerly, endometrial carcinomas were divided into type I and type II cancers; however, recent molecular advances have led to a more nuanced classification system that incorporates mismatch repair status, POLE mutations, and the overall burden of copy-number alterations. In this chapter, we focus on low-grade endometrial endometrioid carcinoma, reviewing histomorphology, grading guidelines, and immunohistochemistry in the context of this new molecular understanding. We address clinical variables such as epidemiology, individual risk factors, and hereditary predisposition syndromes and give an overview of current pathologic staging recommendations, with emphasis on problematic areas. Finally, we discuss ancillary testing including Lynch syndrome screening approaches.