Purpose <p>Social life cycle assessment (S-LCA) has developed as a methodology to assess the social performance or impacts of products and organizations from the life cycle perspective. While the methodology is gaining relevance, it still faces several fundamental methodological challenges, particularly related to primary data-based S-LCA. This commentary paper presents and discusses the most urgent methodological challenges to resolve, suggesting an action plan for the S-LCA community.</p> Methods <p>This paper is a conceptual analysis based on a non-systematic review of current S-LCA literature as well as the authors’ prior experiences in both conducting and systematically reviewing primary data-based S-LCA case studies.</p> Results and discussion <p>Many of the most urgent methodological issues within S-LCA are also among the most difficult to resolve. Priority areas include the development of impact pathways based on cause-effect mechanisms from social sciences research, as well as the standardization of the reference scale approach to improve consistency across studies. Additionally, research on the role of the functional unit in S-LCA is needed, as most studies omit relating results to the functional unit. Many of the challenges encountered during primary data collection can be improved by looking to established methodologies in social sciences. Further, a robust approach for combining primary and secondary data is needed to maintain the life cycle perspective in S-LCA studies.</p> Conclusions <p>A coordinated research agenda is needed to make progress towards addressing these topics so S-LCA can reach widespread applicability. Progress in these areas is essential for strengthening primary data-based S-LCA and enabling its integration within life cycle sustainability assessment (LCSA).</p>