Purpose: A lack of diversity has been observed in radiation oncology (RO), with women and certain racial/ethnic groups underrepresented as trainees, faculty, and practicing physicians. We sought to gain a nuanced understanding of how to best promote diversity, equity, and inclusion (DEI) based on the insights of RO department chairs, with particular attention given to the experiences of the few women and underrepresented minorities (URMs) in these influential positions. Methods and Materials: From March to June 2016, we conducted telephone interviews with 24 RO department chairs (of 27 invited). Purposive sampling was used to invite all chairs who were women (n = 13) or URMs (n = 3) and 11 male chairs who were not URMs. Multiple analysts coded the verbatim transcripts. Results: Five themes were identified: (1) commitment to DEI promotes quality health care and innovation; (2) gaps remain despite some progress with promoting diversity in RO; (3) women and URM faculty continue to experience challenges in various career domains; (4) solutions to DEI issues would be facilitated by acknowledging realities of gender and race; and (5) expansion of the career pipeline is needed. Conclusions: The chairs' insights had policy-relevant implications. Bias training should broach tokenism, blindness, and intersectionality. Efforts to recruit and support diverse talent should be deliberate and proactive. Bridge programs could engage students before their application to medical school.