Book excerpt: Principals have been expected to serve as managers and leaders of curriculum and instruction while facing intense accountability and had to be good communicators capable of building relationships within their school and with community stakeholders. School complexity increased challenges leaders faced, so educational leaders utilized research-based strategies to develop professional resilience and grow in the face of adversity. In preparation for school principalship, assistant principals needed to move beyond school operation and management roles to become a viable candidate for career advancement. Limited research exists describing the preparation of assistant principals for advancement. The purpose of this convergent mixed methods research study was to examine the relationship between beliefs and perceived experiences during assistant principalship and readiness to assume the role of principal. The 33 participants in this study were public school principals currently employed in a school district in Middle Georgia. The three data sources in this study included a Demographic Survey, Principal Readiness Inventory, and Qualitative Questionnaire, which were combined into one online measure for data collection purposes. A stepwise multiple regression analysis was conducted using the quantitative data, and a thematic analysis was utilized to analyze the qualitative data by principal readiness group. According to the data collected, participants reported higher levels of mentoring prior to the initial educational leadership certification compared to the level of mentoring after the initial educational leadership certification. This information could be useful in developing effective leadership development programs that would help assistant principals make a transition into the principalship role.