Purpose and context: This paper aims to establish principles for the increased application and use of life cycle sustainability assessment (LCSA). Sustainable development (SD) encompassing resilient economies and social stability of the global system is growingly important for decision-makers from business and governments. The “17 SDGs” emerge as a high-level shared blueprint for peace, abundance, and prosperity for people and the planet, and “sustainability” for supporting improvements of products and organizations. A “sustainability” interpretation—successful in aligning stakeholders’ understanding—subdivides the impacts according to a triple bottom line or three pillars: economic, social, and environmental impacts. These context and urgent needs inspired the LCSA framework. This entails a sustainability assessment of products and organizations in accordance with the three pillars, while adopting a life cycle perspective. Methods: The Life Cycle Initiative promotes since 2011 a pragmatic LCSA framework based on the three techniques: LCSA = environmental life cycle assessment (LCA) + life cycle costing (LCC) + social life cycle assessment (S-LCA). This is the focus of the paper, while acknowledging previous developments. Identified and reviewed literature shows challenges of addressing the three pillars in the LCSA framework implementation like considering only two pillars; not being fully aligned with ISO 14040; lacking interconnectedness among the three pillars; not having clear criteria for results’ weighting nor clear results’ interpretation; and not following cause-effect chains and mechanisms leading to an endpoint. Agreement building among LCSA experts and reviewing processes strengthened the consensus on this paper. Broad support and outreach are ensured by publishing this as position paper. Results: For harmonizing practical LCSA applications, easing interpretation, and increasing usefulness, consensed ten LCSA principles (10P) are established: understanding the areas of protection, alignment with ISO 14040, completeness, stakeholders’ and product utility considerations, materiality of system boundaries, transparency, consistency, explicit trade-offs’ communication, and caution when compensating impacts. Examples were provided based on a fictional plastic water bottle Conclusions: In spite of increasing needs for and interest in SD and sustainability supporting tools, LCSA is at an early application stage of application. The 10P aim to promote more and better LCSA applications by ensuring alignment with ISO 14040, completeness and clear interpretation of integrated results, among others. For consolidating its use, however, more consensus-building is needed (e.g., on value-laden ethical aspects of LCSA, interdependencies and interconnectedness among the three dimensions, and harmonization and integration of the three techniques) and technical and policy recommendations for application.