Sustainability assessment is an integrated, cross-cutting analytical approach that makes it possible to determine whether a structuring intervention has a development trajectory that is ecologically livable, economically viable, and socially acceptable in the long term. It mobilizes tools that enable the principles of sustainable development to be taken into account in human actions and activities. The aim of this chapter is to demonstrate the contribution of life cycle assessment (LCA) to the assessment of sustainability and to promote its use. Specifically, the aim is to characterize sustainability, determine the links between LCA and sustainability assessment (SA), and identify the boundaries of LCA. The study uses a descriptive approach based on a review of the literature and case studies. It also uses the strengths, weaknesses, opportunities, and threats (SWOT) matrix to identify the limits of LCA. The results highlight the characteristics of LCA that allow it to be used to assess sustainability. LCA in its different forms allows to draw up an overall environmental profile, to identify the main contributors and the costs associated with potential impacts throughout the life cycle of products and services, and to quantify these impacts. In this respect, it seems relevant for determining the trajectory toward sustainable development. This study is part of an educational approach designed to facilitate the understanding and use of LCA as an impact analysis tool. However, this methodology remains fairly complex to implement and requires a certain mastery of impact assessment tools and techniques. The publication of transparent and critical studies would strengthen the credibility of this tool, encourage its dissemination without abusing it, and advance its design and implementation in future.