This article explores the impact of superdiversity on linguistic practices in Southampton, UK. Our focus seeks to identify what these practices are in an environment that we describe as superdiverse, and what is influencing, determining, shaping and contributing to these practices. Southampton is characterised by twenty-first century social mobilities typical of a port city, with a workforce that consists both of those who have settled here for decades, as well as others who are part of the European "new" migration, or who belong to the large international university student population. Our findings arise from a series of linked studies exploring social and linguistic cohesion in Southampton. These provide us with data on the negotiations implicit in the networks that structure urban multilingualism, and allow us to focus above all on examining the impact of our research on the language sensitisation of these communities. We explore the workplaces in a range of sites (public and private, large and small), comprising many nationalities, ethnicities and languages, and representing microcosms of complex, social hierarchies. Our approach is a grassroots, participatory one, seeking to involve our informants with our findings and sharing our analyses and recommendations.