This study involved the assessment of the mobility of public school teachers and its effects on academic performance. Despite the efforts made by the Ministry of Education and Vocational training (MoEVT) to train many teachers and hence to expand secondary schools but it has been revealed that there has been acute shortage of teachers, thus undermining the quality of education in Tanzania. For this reason the study aimed at examining causes, effects and strategies of curbing frequent teachers’ mobility. Both qualitative and quantitative types of research design were applied and the data collection methods included interviews, likert scale, questionnaire and documentation. The sampling techniques were multi-stage, purposive and simple random sampling and respondents were D S E O, heads of schools, teachers and students. The study revealed that teachers’ mobility was caused by teachers’ maternity leave, teachers’ transfer, change of profession or other career such as to join in a business, leaves for training, moved from public to private schools and quit the job. The effects on teachers’ mobility were- It takes a long time to replace another new teacher, subjects remains untaught for an unknown period, students felt bad, performed poorly academically, and lost hope of getting another new teacher after one to leave. The efforts in place to curb mobility of teachers were organizing workshop and seminars and academic contribution from the parents to motivate teachers. To conclude that there is a need to take possible measures to replace a teacher as soon as possible, particularly when one went for maternity leave, training and shifted to private schools.