Scientific literacy is described as the “ability to engage with science-related issues, and with the ideas of science, as a reflective citizen” (OECD 2013 p7). The scientifically literate individual can explain phenomena scientifically, evaluate and design scientific enquiry, and interpret data and evidence scientifically (OECD 2013). Student-led socio-scientific inquiry has been used to develop and assess many skills associated with scientific literacy. The new Irish Junior Cycle science specification includes the Science in Society Investigation (SSI) which aims to assess students’ ability to research a socio-scientific issue, analyse information and secondary data, evaluate claims and opinions and draw evidence-based conclusions (NCCA 2016 p10). The SSI will be carried out by students with the support and guidance of the teacher and student performance will be assessed by the teacher (NCCA 2016 p10). The SSI will be carried out in Irish schools from December 2018 and therefore current pre-service teachers need to be prepared to facilitate and assess the student learning. This study aims to investigate the assessment and development of scientific literacy through student-led socio-scientific inquiry. It was modelled on the Junior Cycle Science in Society Investigation (SSI) and carried out by pre-service teachers (PSTs) as part of a series of lessons on inquiry based teaching. The study was conducted over two years with PSTs in the second year of a concurrent BSc in science education in mathematics, chemistry or physics teaching at secondary level. Thematic analysis was used to analyse data collected from PSTs on their experience of and the competencies developed in the SSI. The competencies that the SSI developed and assessed will be discussed in the context of the PISA framework for scientific literacy. The findings of this study will inform future classroom practices in the facilitation and assessment of socio-scientific research.