Using a blend of functional, distributed, and instructional leadership theories as a theoretical lens, this article presents the perspectives of Namibian principals, heads of departments (HODs) and teachers on the various leadership competencies that are required in their role of enabling school leaders to support their teachers' professional development. The study was approached from a pragmatist perspective employing a mixed-methods methodology. The sequential explanatory design employed combined quantitative and qualitative data obtained from school principals, HODs and teachers. Analysis entailed the generation of descriptive statistics using SPSS and open coding of qualitative data to generate themes. It was found that school leaders require multiple competencies, such as accountability, effective communication, good interpersonal relations, subject-matter competencies, administrative competencies, digital competencies and listening skills to be able to support their teachers' professional development efforts. This study provides insights into how school leadership competencies enable principals' and HODs to support teacher professional development within a Namibian context. The study also provides a new knowledge base for Namibian policy makers, political office bearers and administrators to avail human and financial resources to capacitate school leaders with much needed competencies to be able support teachers' professional development through training.