This study was carried out to explore the influence of Decentralization Policy on graduation rates. The study employed a descriptive survey research that targeted 95 public primary schools in Missenyi District from where study respondents were randomly selected. A sample size of 140 was used which comprised 3 members of School Management Committee, 7 Ward Education Officers, 40 head teachers and 90 classroom teachers. The questionnaire was the main instrument for data collection. Collected data were analyzed using Statistical Package for Social Sciences (SPSS) software and presented using tables, frequencies, and percentages. The study found out that decentralization policy positively and significantly influences graduation rate in primary schools in Missenyi District in Tanzania. From these findings, it was concluded that decentralization policy has led to increased graduation rates. The researcher recommends that government agents and educational stakeholders should ensure higher level of internal efficiency to enhance the benefits of decentralization policy. Lastly, the study recommends further systematic research areas of decentralization policy and external efficiency of education system, organizational effectiveness and organizational commitment.