As nursing leaders, nurse managers are critical to the future of the healthcare system, as well as the nursing profession. Becoming a new manager or leader requires considerable development (Conners, Dunn, Devine, & Osterman, 2007); however, there is limited literature that focuses on the development of the nurse manager (Cadmus & Johansen, 2012). The purpose of this study was to explore the development of self-efficacy in nursing leaders, specifically new nurse managers. Albert Bandura’s (1997) self-efficacy theory was used to guide this study. Qualitative content analysis was used to analyze the data. Two themes emerged from the data, describing experiences of self-efficacy, and the development of self-efficacy. A positive connection between experiencing a mentoring relationship and perceived self-efficacy emerged from the data. The findings of this study provide healthcare stakeholders an in-depth understanding of the importance of mentoring and it outcomes related to the development of self-efficacy in new nurse managers.