This article focuses on the experience of a bilateral educational aid project concerning a continuing professional development (CPD) programme for teachers with specific reference to Guinea-Bissau. The authors were keen to understand how teachers and school principals perceived the impact of this CPD programme on the quality of teaching and learning. In this qualitative study, data from teachers and school principals were collected by means of interviews, focus groups and field notes. The article argues that the programme improved the language skills of the teachers and impacted positively on scientific, pedagogical, and didactic content.