Abstract Background Mental health is the leading cause of disability worldwide. In the wake of both a civil war and an Ebola outbreak, Sierra Leone ranks as one of the lowest ranked countries on the Human Development Index (UNDP. Human Development Report 2015, Work for Human Development. The United Nations Development Programme; 2015). The WHO identified Sierra Leone among its priority countries for the piloting of its Mental Health Gap Action Programme (mhGAP). Aligned to these efforts, CBM and their affiliated partners employed the use of Community Mental Health Forums (CMHFs), facilitated by Mental Health Nurses (MHNs), as a sensitive and practical way of engaging key community stakeholders to discuss and address issues of mental health. This study sought firstly, to identify factors that affect the successful implementation of CMHFs, as identified by programme participants. Second, the study sought to identify what changes participants perceived as having taken place as a result of their participation in CMHFs. Methods 10 MHNs and 52 forum participants were purposely selected to take part in key informant interviews and focus group discussions, conducted across eight districts in Sierra Leone. Interview transcripts were analysed across four rounds of coding, using a mixture of deductive and inductive approaches. Results Results identified three themes, Traditional Beliefs and Culture; Health System; and Inclusive Approaches as affecting the implementation of CMHFs in their districts. Participants further perceived that their participation in the Community Mental Health Forums resulted in changes taking place across the themes of Awareness and beliefs, Behaviours towards people experiencing psychological distress, and as leading to greater Collaboration and cooperation between formal and informal mental health practitioners. Conclusions Results are discussed in the context of the extant literature and a novel framework, that incorporates multiple best practice recommendations and factors which influence the successful implementation of CMHFs is put forward.