This study investigates the influence of leadership and management practices on student achievement in public primary schools in Endebess Sub-County, Trans Nzoia County, where academic performance remains below the national average despite infrastructural improvements and increased teacher deployment. Drawing on Transformational Leadership and Social Interdependence theories, the research focuses on vision setting, collaboration, staff development, and stakeholder communication as key drivers of academic outcomes. Using a quantitative survey and correlational design, data was collected from 331 education leaders and analyzed through descriptive and regression methods. The findings aim to inform school leadership strategies and enhance institutional effectiveness. The study findings on staff development indicated that respondents generally held favourable views regarding the relevance and impact of professional training, particularly in enhancing their teaching or administrative roles and contributing to student achievement. The study concluded that staff development had a statistically significant positive relationship with academic performance. The study recommended that, The Ministry of Education, in collaboration with the Teachers Service Commission, should establish uniform staff development frameworks that ensure equitable access to quality training across all zones of Endebess Sub-County. It was also recommended that school leadership should periodically assess staff development needs to tailor training content to specific instructional and administrative gaps.