Abstract The paper explains and discusses the challenges confronted during the application of the Social Life Cycle Assessment (S-LCA) methodology defined by UNEP/SETAC S-LCA guidelines in a case study under the framework of Life Cycle Sustainability Assessment (LCSA). The environmental, economic and social aspects related to two mineral fertilizers and one industrial compost were assessed. The system boundaries of the LCSA study included fertilizer production and transportation and certain stages of cultivation. Regarding S-LCA, background and foreground processes were taken into account. The Social Hotspots Database (SHDB) was used to include social aspects related to background processes. Following the approach of Life Cycle Attribute Assessment – proposed, e.g., in the S-LCA Guidelines – the amount of working time that had been spent on each unit process was used to aggregate the social aspects over the life cycle. This work is one of the first examples for applying the S-LCA Guidelines within the LCSA framework, as well as for using SHDB in a real case study. The comparability and reliability of the S-LCA results were highly challenged by the definition of the functional unit and the system boundaries, the choice of stakeholders and indicators, the use of working time for aggregating social aspects and the data availability among others. Regarding the latter, it is necessary to find a balance between the use of site-specific primary data and generic data to include the entire life cycle. In addition, for many social indicators, no definition of the social targets to achieve is currently agreed upon in the international community. Thus, a complete and robust interpretation of the S-LCA results is not yet possible because of the many methodological obstacles faced. However, because the social dimension plays a major role in sustainability assessment, and as there is no commonly agreed methodology, every effort to advance the application for S-LCA is highly recommended.