The recent implementation of CEFR-aligned Classroom-Based Assessment (CEFR CBA) requires teachers to conduct comprehensive assessments of their students as part of their teaching and learning practises. Regarding this reform, the teachers' professional development (TPD) programme plays a crucial role in ensuring that teachers are well-equipped with the content and pedagogical understanding of the new policy. The TPD becomes an important medium with the aim of enhancing teachers’ professionalism to suit the need of education reform. Therefore, the purpose of this study was to investigate the implementation of teachers' professional development at the meso (school) and macro (education department) levels by identifying the types of TPD strategies employed by trainers. This study also investigates the challenges preventing the TPD programme from effectively function in disseminating information to teachers. By using the qualitative approach and semi-structured interviews, data was collected to address research objectives. Overall, this study found that the implementation of the TPD programme for CEFR CBA was ineffective as it was highly transmissive but lacked the practicality required to ensure the dissemination of knowledge throughout the entire cascade system. Several obstacles, including the uncertainty of conducting in-house training, non-option teachers, participant engagement, and limited time, impede the TPD's ability to fulfil its purpose of coaching and mentoring teachers to implement the CEFR CBA. This study suggests that programme designers and trainers should better equip TPD by addressing the needs of teachers at the micro level.