Bringing together the complex social and cultural dimensions of marine spatial planning (MSP), this chapter examines how these two terms are applied (or not) in the context of MSP. Global marine and coastal planning continues to recognise that human activities must be considered in order to account for the dynamic interconnectivity between society and the sea. Many research fields explore the importance of the sea to identity, sense of place, health or community cohesion. However, these draw on a range of different assumptions to mainstream marine science and struggle to be incorporated into traditional policy processes, environmental assessments and large-scale planning processes. In this chapter, we interrogate the concept of ‘socio-cultural’, examining how this is being defined and applied across the MSP landscape.