Diaspora are frequently hailed as a source of knowledge and skills for countries of origin. Short-term diaspora return and temporary return programmes emerged in the 1970s. Since this time, several different programmes have emerged for diaspora contributions to development in Africa. Little research, however, has been conducted on the effectiveness of these programmes and the specific modalities that enable diaspora to achieve successful knowledge transfer that is sustainable over time. This chapter draws on research conducted within the programme Connecting Diaspora for Development (CD4D), administered by IOM, the Netherlands, from 2017 to 2019. Case examples illustrate the experiences of participants and the institutions in the origin countries hosting the diaspora member in Sierra Leone and Somaliland with regard to knowledge transfer and, subsequently, how the knowledge transfer contributes to capacity building and changes at the organization. Data was collected in Sierra Leone and Somalia in 2017–2019. This chapter illustrates two common forms of knowledge transfer within CD4D, formal trainings and closely working together, and shows how diaspora experts contribute to individual capacity building as well as to the introduction of new procedures in the host institutions.