This study assessed instructional leadership practices and teachers' job performance in public primary schools in Osogbo Local Government Area, Osun State, Nigeria. A descriptive survey research design was adopted, with a sample of 100 teachers selected through stratified sampling technique. Two validated instruments-Instructional Leadership Practices Questionnaire (ILPQ) and Teachers' Job Performance Scale (TJPS) were used for data collection. Face and content validity of the instruments were established by experts in Educational Management and Measurement and Evaluation. Reliability was determined using Cronbach Alpha method, yielding coefficients of 0.81 for ILPQ and 0.84 for TJPS. Data were analyzed using descriptive statistics of mean and standard deviation to answer the research questions. Findings revealed a positive relationship between instructional leadership practices and teachers' job performance (overall mean = 2.98), with professional development support (mean = 3.65) and curriculum supervision (mean = 3.30) as key contributors. However, school leaders face significant challenges including teacher resistance to new practices (mean = 3.83), limited time for supervision (mean = 3.65), and insufficient leadership training (mean = 3.49). The study concludes that while instructional leadership positively influences teacher effectiveness, its implementation is hindered by systemic and human factors. Recommendations include establishing structured professional development programs for school leaders, improving resource allocation for instructional support, and fostering collaborative school cultures to minimize resistance to change.