Purpose To summarize the results of American Society for Radiation Oncology (ASTRO)’s analysis of appropriate delivery of postoperative radiation therapy (RT) for endometrial cancer using the RAND/University of California, Los Angeles (UCLA) Appropriateness Method, outline areas of convergence and divergence with the 2014 ASTRO endometrial Guideline, and highlight where this analysis provides new information or perspective. Methods and materials The RAND/UCLA Appropriateness Method was used to combine available evidence with expert opinion. A comprehensive literature review was conducted and a multidisciplinary panel rated the appropriateness of RT options for different clinical scenarios. Treatments were categorized by the median rating as Appropriate, Uncertain, or Inappropriate. Results The ASTRO endometrial Guideline and this analysis using the RAND/UCLA Appropriateness Method did not recommend adjuvant RT for early-stage, low-risk endometrioid cancers and largely agree regarding use of vaginal brachytherapy for low-intermediate and high-intermediate risk patients. For more advanced endometrioid cancer, chemotherapy with RT is supported by both documents. The Guideline and the RAND/UCLA analysis diverged regarding use of pelvic radiation. For stages II and III, this analysis rated external beam RT plus vaginal brachytherapy Appropriate, whereas the Guideline preferred external beam alone. In addition, this analysis offers insight on the role of histology, extent of nodal dissection, and para-aortic nodal irradiation; the use of intensity modulated RT; and management of stage IVA. Conclusions This analysis based on the RAND/UCLA Method shows significant agreement with the 2014 endometrial Guideline. Areas of divergence, often in scenarios with low-level evidence, included use of external beam RT plus vaginal brachytherapy in stages II and III and external beam RT alone in early-stage patients. Furthermore, the analysis explores other important questions regarding management of this disease site.