While there is growing critique emerging to address social sustainability in marine/maritime spatial planning (MSP), overwhelmingly attention has been on governance, economic and environmental aspects. This chapter redresses this by proposing a conceptual framework to elucidate key features of social sustainability in MSP. The ambition is to both note the existing critique of MSP and go beyond it by more clearly and comprehensively articulating how social sustainability could be conceived in MSP, as well as how this framework could be applied to analyse MSP practice. Key features of social sustainability elaborated are: deepening democratic decision-making, inclusion of socio-cultural values and knowledge, equitable distribution and social cohesion. Finally, the chapter concludes by nominating strategies to give greater visibility to social sustainability as a key MSP concern.