Mental health professionals in all settings work with clients who are affected by trauma. Traumatic events expose mental health professionals to the negative psychological and emotional impact of witnessing and listening to client stories. Vicarious trauma is the emotional consequence of this empathic engagement with clients. The purpose of this correlational study was to identify predictors of vicarious trauma in mental health professionals that had not been studied before. The theoretical framework guiding the study was the Bowen family systems theory and the construct of differentiation of self. A regression analysis was conducted with a purposive sample of 83 licensed or certified mental health professionals from community counseling agencies in the Midwest. Five research questions were evaluated using multiple regression analysis and determined that subcomponents of differentiation of self (i.e., emotional reactivity, I position, emotional cutoff, and fusion with others) predicted vicarious trauma. An additional regression analysis showed that vicarious trauma was best predicted by 2 subcomponents of differentiation of self; emotional reactivity was the most significant predictor followed by I position. By identifying characteristics in mental health professionals that predict vicarious trauma, counselor educators and supervisors can better educate, train, develop programs, and advocate for the emotional welfare of mental health professionals in the field. [The dissertation citations contained here are published with the permission of ProQuest LLC. Further reproduction is prohibited without permission. Copies of dissertations may be obtained by Telephone (800) 1-800-521-0600. Web page: http://www.proquest.com/en-US/products/dissertations/individuals.shtml.]