Professional development is a process by which a person acquires and maintains personal and professional abilities and skills, which leads to increased competence in their field. Professional development for school leaders is therefore crucial to providing opportunities for them to reflect on their practice, debate issues about their work, and develop strategies to improve their teaching and leadership practice. This study is concerned with the professional development of school leaders in Makira Ulawa Province (MUP) in Solomon Islands. In particular, it investigates the impact of a New Zealand Aid funded Professional Development Programme (PDP) on developing head teachers’ understandings of their roles and responsibilities, and on increasing their effectiveness. While much research on professional development (PD) of head teachers has been conducted, especially in developed countries, very little research has been carried out in Melanesian countries such as Solomon Islands. Thus very little is known about the professional development of head teachers in Solomon Islands. For this study data were collected using semi-structured interviews. Interviews were conducted with five rural primary school head teachers who had participated in the PDP and the two facilitators who were involved in leading it. A thematic analysis approach was used to analyse the data and six themes were identified: learning experiences of the head teachers during the PDP; positive impacts of the PDP; cooperation; the head teachers’ views on PD and learning; the facilitators’ views on the PDP; and the challenges experienced by the facilitators and head teachers. The findings show that head teachers’ PD of the kind provided by the PDP needs to be on-going and a career-long developmental process so that head teachers can sustain, enhance, and put into action the knowledge and skills they gain. School based PD of head teachers through programmes such as the PDP has potential and is appropriate for developing countries such as Solomon Islands. For such programmes to be consistently successful however, they need to be tailored to the local education context and needs of the head teachers, and conducted for an appropriate length of time. This study highlights the need to provide effective PD programmes for school leaders and has identified important implications for the development and effectiveness of head teachers in Solomon Islands. It has been concluded that Solomon Islands should aim to develop a national on-going PD programme for school leaders with an emphasis on a school-based approach which involves local support personnel.