In this study, propensity score matching (PSM) was conducted to examine differences in the effectiveness of research mentor training (RMT) implemented using two modes--face-to-face or synchronous online training. This study investigated each training mode and assessed participants' perceived gains in mentoring skills, ability to meet mentees' expectations, and overall quality of mentoring, as well as intention to make changes to their mentoring practices. Additional factors that may contribute to participant outcomes were also examined. In total, 152 mentors trained using a synchronous online platform and 655 mentors trained in in-person workshops were analyzed using the PSM method. Mentors were matched based on similar characteristics, including mentee's career stage, mentor's title, mentor's prior mentoring experience, mentor's race/ethnicity and sex, and mentor's years of experience; results show that both face-to-face and synchronous online modes of RMT are effective. Findings indicated that the training mode did not significantly impact the mentors' perceived training outcomes. Factors associated with the reported training outcomes included dosage (hours of training), facilitator effectiveness, race/ethnicity, and previous mentoring experience. The results of this study demonstrate that mentors' perceived training outcomes are comparable regardless of the training modality used--online versus face-to-face.