To determine if specialty, among other professional development and demographic variables, predicted MD-PhD program graduates' research engagement. The authors merged the 2015 Association of American Medical Colleges (AAMC) National MD-PhD Program Outcomes Survey database with selected data from the AAMC Student Records System, Graduation Questionnaire, and Graduate Medical Education (GME) Track Resident Survey. At the person level, they tested variables of interest for independent associations with MD-PhD graduates' research engagement using chi-square, Pearson correlations, and analysis of variance tests and logistic and linear regressions. Of 3,297 MD-PhD graduates from 1991-2010 who were no longer in GME training in 2015, 78.0% (2,572/3,297) reported research engagement. In models controlling for several variables, a neurology (vs internal medicine; adjusted odds ratio [AOR]: 2.48; 95% confidence interval [CI]: 1.60-3.86) or pathology (vs internal medicine; AOR: 1.89; 95% CI: 1.33-2.68) specialty, full-time faculty/research scientist career intention at graduation (vs all other career intentions; AOR: 3.04; 95% CI: 2.16-4.28), and ≥ 1 year of GME research (vs no GME research year[s]; AOR: 2.45; 95% CI: 1.96-3.06) predicted a greater likelihood of research engagement. Among graduates engaged in research, the mean percentage of research time was 49.9% (standard deviation 30.1%). Participation in ≥ 1 year of GME research (beta [β] coefficient: 7.99, P < .001) predicted a higher percentage of research time, whereas a radiation oncology (β: -28.70), diagnostic radiology (β: -32.92), or surgery (β: -29.61) specialty, among others, predicted a lower percentage of research time (each P < .001 vs internal medicine). Most MD-PhD graduates were engaged in research, but the extent of their engagement varied substantially among specialties. Across specialties, participation in research during GME may be one factor that sustains MD-PhD graduates' subsequent early- to midcareer research engagement. Copyright © 2020 by the Association of American Medical Colleges.