<p style="text-align: justify;">Teachers play an important role in helping students improve their learning and achieve the intended curriculum outcomes. Therefore, it is essential to look at teachers’ knowledge, understanding, and perceptions of any educational innovation. The present study aims to examine knowledge, understanding and perceptions of Rwandan science teachers with respect to the competence-based curriculum (CBC) introduced in 2015. The 2015 curriculum framework included features like the rationale for its adoption, the concept of competence, different competences to be developed by learners upon CBC implementation, principles guiding CBC implementation, and cross-cutting issues to be addressed by CBC implementation. This research is a multiple case study that adopted a qualitative approach with interpretivism paradigm. Twelve science teachers from three secondary schools, selected based on their differing teaching experience, participated in the study. Data were collected through semi-structured face-to-face interviews. The data were transcribed and qualitatively analyzed using content analysis. The findings revealed some satisfactory knowledge, understanding and perceptions of science teachers. Further, knowledge and understanding gaps as well as negative perceptions of CBC were identified. Towards the effective and efficient implementation of the CBC, this research suggests appropriate training and establishment of the school community of practices for improving teachers’ experience of the CBC.</p>