In this paper, a tool for prioritising social sustainability parameters in product development is described. The tool's core element is a two-step Delphi exercise carried out in the product development team. The purpose of the tool is to (i) select critical social impact indicators suitable for guiding the product development process, (ii) enhance the product development team’s understanding in the field of social sustainability and (iii) engage the team in the sustainability assessment, with the further aim of ensuring the assessment’s influence on the product development process. Applied in a real product development project, the tool proved successful for selecting indicators and increase understanding of social sustainability within the product development team. Selected indicators' usefulness for the product development process remains an open question to be addressed later on as the project evolves.