Sustainable development (SD) is generally recognised as having three dimensions, ecological, economic and social. Yet, its implementation is burdened with resistance and conflict rooted in the short-term 'business as usual' development model, opposed to the long-term sustainable benefit of local communities. Hence, the development of strategies to implement SD projects may require further differentiation of these dimensions in relation to the contextual situation in which the project resides. In two studies of SD projects on the Croatian islands, we identify five interlocking spheres of importance, Spiritual, Political, Economic, Educational and Health, in addition to Ecological. Each of these spheres is accessible through gate-keepers, individuals or a group of people who have the authority over the sector and as such, significantly influence public opinion. We suggest that in this particular island context the sustainability of these projects may lie with those gate-keepers. Hence, initiating and maintaining SD projects in these contexts requires a structured and targeted lobbying of these gate-keepers.