Background: Treating opioid use disorder (OUD) with buprenorphine or methadone significantly reduces overdose and all-cause mortality. Prior studies demonstrate that clinicians and residents reported a lack of preparedness to diagnose or treat OUD. Little is known about how clinical exposure or buprenorphine X-waiver training impacts OUD care delivery by resident physicians. Objective: Distinguish the effects of X-waiver training and clinical exposure with OUD on resident’s knowledge, attitudes, feelings of preparedness, and practices related to OUD treatment provision. Methods: From August 2021 to April 2022, we distributed a cross-sectional survey to internal medicine residents at a large academic training program. We analyzed associations between self-reported clinical exposure and X-waiver training across 4 domains: knowledge about best practices for OUD treatment, attitudes about patients with OUD, preparedness to treat OUD, and clinical experience with OUD. Results: Of the 188 residents surveyed, 91 responded (48%). A majority of respondents had not completed X-waiver training (60%, n = 55) while many had provided clinical care to patients with OUD (65%, n = 59). Most residents had favorable attitudes about OUD treatment (97%). Both residents with clinical exposure to treating OUD and X-waiver training, and residents with clinical exposure without X-waiver training, felt more prepared to treat OUD ( P < .0008) compared to residents with neither clinical exposure or X-waiver training or only X-waiver training. Conclusions: Residents with clinical exposure to treating OUD are more prepared to treat patients with OUD than those without clinical exposure. Greater efforts to incorporate clinical exposure to the treatment of OUD and education in internal medicine residency programs is imperative to address the opioid epidemic.