ImportancePhysician burnout disproportionately affects women physicians and begins in training. Professional coaching may improve well-being, but generalizable evidence is lacking.ObjectiveTo assess the generalizability of a coaching program (Better Together Physician Coaching) in a national sample of women physician trainees.Design, Setting, and ParticipantsA randomized clinical trial involving trainees in 26 graduate medical education institutions in 19 states was conducted between September 1, 2022, and December 31, 2022. Eligible participants included physician trainees at included sites who self-identified as a woman (ie, self-reported their gender identity as woman, including those who reported woman if multiple genders were reported).InterventionA 4-month, web-based, group coaching program.Main Outcomes and MeasuresThe primary outcomes were change in burnout (measured using subscales for emotional exhaustion, depersonalization, and personal achievement from the Maslach Burnout Inventory). Secondary outcomes included changes in impostor syndrome, moral injury, self-compassion, and flourishing, which were assessed using standardized measures. A linear mixed model analysis was performed on an intent-to-treat basis. A sensitivity analysis was performed to account for the missing outcomes.ResultsAmong the 1017 women trainees in the study (mean [SD] age, 30.8 [4.0] years; 540 White participants [53.1%]; 186 surgical trainees [18.6%]), 502 were randomized to the intervention group and 515 were randomized to the control group. Emotional exhaustion decreased by an estimated mean (SE) −3.81 (0.73) points in the intervention group compared with a mean (SE) increase of 0.32 (0.57) points in the control group (absolute difference [SE], −4.13 [0.92] points; 95% CI, −5.94 to −2.32 points; P < .001). Depersonalization decreased by a mean (SE) of −1.66 (0.42) points in the intervention group compared with a mean (SE) increase of 0.20 (0.32) points in the control group (absolute difference [SE], −1.87 [0.53] points; 95%CI, −2.91 to −0.82 points; P < .001). Impostor syndrome decreased by a mean (SE) of −1.43 (0.14) points in the intervention group compared with −0.15 (0.11) points in the control group (absolute difference [SE], −1.28 (0.18) points; 95% CI −1.63 to −0.93 points; P < .001). Moral injury decreased by a mean (SE) of −5.60 (0.92) points in the intervention group compared with −0.92 (0.71) points in the control group (absolute difference [SE], −4.68 [1.16] points; 95% CI, −6.95 to −2.41 points; P < .001). Self-compassion increased by a mean (SE) of 5.27 (0.47) points in the intervention group and by 1.36 (0.36) points in the control group (absolute difference [SE], 3.91 [0.60] points; 95% CI, 2.73 to 5.08 points; P < .001). Flourishing improved by a mean (SE) of 0.48 (0.09) points in the intervention group vs 0.09 (0.07) points in the control group (absolute difference [SE], 0.38 [0.11] points; 95% CI, 0.17 to 0.60 points; P < .001). The sensitivity analysis found similar findings.Conclusions and RelevanceThe findings of this randomized clinical trial suggest that web-based professional group-coaching can improve outcomes of well-being and mitigate symptoms of burnout for women physician trainees.Trial RegistrationClinicalTrials.gov Identifier: NCT05222685