Dissertation (MA Education)The purpose of this study was to investigate the impact of Open Performance Review and Appraisal System in improving teachers' work performance in Tanzanian primary schools, Sikonge District Council being the case study. The study was guided by New Public Management Theory (NPM). The research predominantly adopted qualitative approach and it employed a descriptive research design targeting 114 participants including 60 teachers and 40 head teachers, 10 Ward Education Coordinators and 4 district education officials comprised of District School Quality Assurer, District Education Officer, District Secretary Teachers‟ Service Commission and Human Resources Officer. The study also employed Simple Random Sampling and Purposive Sampling as the sampling techniques. Furthermore, semi- structured interviews, questionnaires (mainly open- ended questions) and documentary review were the main instruments used in this study. The findings indicated that OPRAS plays a significant role in improving teachers' work performance in primary schools. It was also found that teachers perceived OPRAS in both positive and negative way. On one hand it was perceived as an important mechanism through which teachers‟ performance can be improved and at the other hand it was perceived as wastage of time and resources with no positive effects in relation to teachers‟ work improvement. It was further found that OPRAS implementation faced a number of challenges such as inadequate knowledge on OPRAS for teachers, and other educational implementers at Ward and district level, poor feedback provision, insufficient motivation and poor working conditions, shortage of resources, both financial and materials resources and lack of commitment and seriousness in implementing the plan. It is recommended that the government needs to take effective measures to mitigate all these challenges especially those related to resources, training and that implementers adhere to the commitment, being responsible and accountable towards the effective implementation of OPRAS.