This qualitative case study examined the self-efficacy beliefs of three middle school principals who had high enrollment and successful completion rates of minority students in Algebra I. With current tracking systems impacting minority student enrollment in rigorous courses, particularly in the area of mathematics, there is a need to explore and analyze the beliefs and practices of successful principals to ensure academic success for minority students in the subject of mathematics, particularly in middle school. To conduct this study, I analyzed transcripts from semi-structured interviews. The findings from this study reinforced the notion that self-efficacy beliefs were largely influenced by mastery experiences and vicarious experiences. The findings from this case study contributed additional knowledge about principal self-efficacy and the need for leadership development programs to help leaders define their own self-efficacy practices as it relates to closing the achievement gap. Examining the self-efficacy beliefs of successful middle school principals who have high minority student success in Algebra supports a compelling way to learn about how school leaders are addressing ways to close the achievement gap between African American and Latino students in comparison to their Asian and White peers. This study has practice implications for school systems interested in building the capacity for principal leadership development programs focused on leaders building a durable sense of self-efficacy to lead middle schools for change. Closing the achievement gap in helping all students to graduate college-ready requires a renewed focus on leadership during the middle school years.