The conventional dualistic model of endometrial cancer (types I and II) has been the mainstay in clinical practice for decades. However, recent advances show that this model does not capture the heterogeneity of endometrial cancer. As a result, there has been a strong demand for a more comprehensive understanding of the molecular and genetic mechanisms underlying endometrial carcinogenesis. This chapter aims to provide a comprehensive overview of the most recent advances in endometrial carcinogenesis with potential clinical implications for diagnosis and management. In particular, we focus on molecular-based classifications of endometrial carcinoma, which have emerged as promising tools for predicting patient prognosis and survival. We also propose a unified pathologic classification for intraepithelial endometrial neoplasia that could facilitate a more accurate diagnosis and risk stratification for patients.