Both island and mountainous settings are often considered fragile and in need of specific approaches to their sustainable development and the building of social, economic and environmental resilience. The Highlands.3 project investigated the range and nature of sustainable development initiatives in mountain areas. One of the in-person collaborative fieldwork sessions during the project took place in the mountainous island archipelago of Cape Verde, off the coast of West Africa. The research sought to understand the specific initiatives taking place in upland areas, within an island setting. This presentation will outline the theoretical overlaps between sustainable development approaches in mountain and island settings, highlighting convergences and divergences between the two. This research consisted of three sequential scoping reviews, followed by an analysis of empirical data gathered in Cape Verde. The first and second scoping reviews considered the nature of sustainable development in mountain and island settings, respectively, while the third considered literature specifically focusing on mountainous islands. Data relating to the island nature of mountainous areas in Cape Verde was extracted from interviews undertaken there, and synthesised with the theoretical foundation. This research is ongoing and as such no specific results can be reported at this time. It is anticipated that a conceptual understanding of the convergences and divergences of sustainable development approaches in these specific geographies can inform future efforts in designing interventions and initiatives.