Competency-based curricula are increasingly popular in schools due to global challenges in science, technology and global market demand. This study explored challenges facing the implementation of a competence-based curriculum in public primary schools to pupils in Same District -Tanzania. The study employed mixed methods and convergent design, using a sample of 289 respondents from 32 public primary schools in Same District. The methods of data collection were questionnaires and interviews. The quantitative data was analyzed using descriptive statistics in terms of percentages and frequencies while qualitative data was analyzed using the thematic approach. Based on the findings, the study concluded that, the implementation of CBC is rendered ineffective due to lack of learner-centred interactive teaching strategies as required by the CBC. The study suggests that the government should organise in-service training for primary school teachers on CBC. It is also recommends provision of adequate instructional resources, such as ICT equipment and audio-visual materials.