Scientific literacy is widely regarded as one of the most important goals of Science Education. Scientific literacy relates to how an individual uses their scientific knowledge and skills to participate as active citizens in society. Research indicates that teaching science through Socioscientific Issues (SSIs) has the potential to achieve this goal. However, there is a dearth of international literature on the impact of SSIs-based education on the development of primary/elementary students’ scientific literacy. Within an Irish context, SSIs-based education is not a feature of the Irish primary science curriculum and therefore its potential is not fully realised and is under examined in the teaching of science.This study sought to explore whether the teaching of primary science through SSIs has an impact on enhancing upper primary school students’ scientific literacy competencies; namely the development of student interest in science, scientific inquiry skills, conceptual understanding of science, Nature of Science (NoS) understanding, socioscientific argumentation and socioscientific reasoning. Seven primary school teachers participated in a professional learning course aimed at developing teacher confidence and competence pertaining to the teaching of primary science through SSIs and associated pedagogies. These teachers and the students in their classes (n=158 students) participated in this multiple-site case study whereby they taught primary science through SSIs over a six-month period. A mixed-methods pragmatic research design was utilised to assess its impact on students’ scientific literacy where multiple data sources were collected concurrently including student questionnaires, student focus group interviews, student practical science skill assessment and teacher semi-structured interviews. Findings indicate that teaching primary science through SSIs had a positive impact on the development of primary school students’ science content knowledge, NoS understanding and scientific inquiry skills. Students were found to have more informed perceptions of school science and its relevance to their everyday lives. Students demonstrated enhanced ability to engage in socioscientific argumentation and in most cases students were able to apply their science content knowledge and skills to socioscientific reasoning whereby students made informed decisions pertaining to SSIs relevant to their everyday lives. Furthermore, some classes participated in student-led active citizenship as they took informed action in response to the SSI. The findings suggest that teaching primary science through SSIs has the potential to develop upper primary school aged students’ scientific literacy competencies where students become prepared and empowered for active and responsible participation in a complex, democratic society. This study recommends that SSIs-based education and scientific literacy competencies be an explicit feature of primary/elementary science curricula both nationally and internationally and that this be supported by teacher professional learning opportunities.