‘Mixed use’ is a solution often used to address (urban) sustainability concerns. The claim is that more compact, high density urban developments that serve a multitude of uses and users can be socially beneficial while being environmentally sound and economically viable. In the case of the Luneside East regeneration project in Lancaster, UK, ‘mixed use’ has been specified towards the goal of achieving a ‘vibrant, sustainable quarter of the city’ and a ‘sustainable and balanced community’. In this paper, a specific dimension of mixed use critical to community sustainability – provision of social infrastructure – is assessed using a futures analysis. Providing services and facilities that meet the needs of residents, promoting social interaction and enhancing overall quality of life are vital for building sustainable communities. However, to deliver these social benefits, one of the conditions is that there is equitable access for residents, both in the new development and for the existing community. The results of the study indicate that this condition is vulnerable in several of the futures analysed. It is important for planners to take account of these findings in order to ensure the Luneside East development will meet its social sustainability objectives both now and in the future.