This study aimed at exploring the difference in learners‟ achievement in public and private primary schools in Tanzania. Three subjects namely Kiswahili, English and Mathematics were assessed to investigate the differences. The specific objectives of the study were; (1) to find out the difference in learners achievement (2) to investigate the factors contributing to the difference. Education for Self-Reliance (ESR) policy was used as theory to guide the study. ESR policy was formulated by Nyerere in 1967 as a critique to colonial education. I used ESR theory in order to make analysis at macro level. Privatization of education has similar impact like those of colonial education in Tanzanian community of today. The conceptual framework was developed from the idea of Sheikh (2006). I used the conceptual framework to make analysis at micro level. The model comprises three components such as enabling conditions, teaching and learning process and outcome. The study was designed in the form of case study. Purposeful and criterion sampling techniques were used to select 2 head teachers, 6 subject teachers, 10 parents and ten pupils who were interviewed. It also involved 102 pupils who did the tests which I administered for the sake of this study. This study was limited to primary schools under the LOITASA project in Tanzania, specifically in Dar es Salaam region. The study mainly employed a qualitative research approach but in some cases even a quantitative approach. Semi structure interviews, observation and documentary review were employed in this study. Content analysis was used for data analysis. The Findings indicated that private primary school pupils performed better than public school pupils. But in the grade four national examinations in mathematics, public primary school did better than private primary schools pupils. The findings also indicated that teachers in public schools lack motivation and commitment to their work due to too small salary, scarcity of teaching resources and denial of their rights and other benefits as well as low status accorded to teachers. The teachers in private schools do not face the above mentioned problems. They are committed and motivated to work hard. They spend most of their time at school performing their teaching roles effectively and efficiently. Moreover, the findings showed that private tuition, provision of sufficient exercises, home assignments and feedback, parental supports and availability of learning materials at home contribute much to learners‟ academic achievements. Learner centered methods and good classroom climate enhance good academic performance. I recommended that there is a need of conducting in-service training, seminars and workshops to teachers to strengthen their existing knowledge and skills. In the case of motivation, teachers‟ living condition can be improved by increasing their salaries. Other fridge benefits also, should be paid attention. Furthermore, there should be regular communication between parents and teachers so as to monitor pupils‟ academic progress.