Leadership matters greatly. A wide body of research has shown that schools with effective leaders mobilize efforts to narrow achievement gaps. As instructional leaders, principals lead professional learning communities in the charge to improve teaching and learning outcomes for all students. Ultimately, school leaders have a complex role and carry the responsibility for continuous improvement. This study explored the oral communications of school leaders during teaching and learning conversations. The researcher employed the Critical Incident Technique approach. Seven school leaders participated in three semi-structured interviews over nine weeks. By highlighting principal talk at the center of collaborative conversations, the language of impact emerged. The findings in this study include a reinforcement with the review of the literature. Key themes surfaced in the areas of principal influence, leveraging leadership language repertoires, and the significance of leadership talk moves on collective impact. The study revealed that talk moves support a variety of purposes. This implies that principal talk is a valuable tool in teaching and learning conversations. This study adds to the current research on leadership communication and leadership impact with implications for principal preparation efforts, educational leadership programs, and professional learning community work. Findings of this current study may serve to benefit district leadership, educational coaches, principals, teacher leaders, and professional learning community teams. [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.bibliotheek.ehb.be/en-US/products/dissertations/individuals.shtml.]