BACKGROUND: Within a Job Demands-Resources Model framework, formal mentoring can be conceived as a job resource expressing the organization's support for new members, which may prevent their being at risk for burnout. OBJECTIVE: This research aims at understanding the protective role of formal mentoring on burnout, through the effect of increasing learning personal resources. Specifically, we hypothesized that formal mentoring enhances newcomers' learning about job and social domains related to the new work context, thus leading to lower burnout. METHODS: In order to test the hypotheses, a multiple regression analysis using the bootstrapping method was used. RESULTS: Based on a questionnaire administered to 117 correctional officer newcomers who had a formal mentor assigned, our results confirm that formal mentoring exerts a positive influence on newcomers' adjustment, and that this in turn exerts a protective influence against burnout onset by reducing cynicism and interpersonal stress and also enhancing the sense of personal accomplishment. CONCLUSIONS: Confirming previous literature's suggestions, supportive mentoring and effective socialization seem to represent job and personal resources that are protective against burnout. This study provides empirical support for this relation in the prison context.