This chapter discusses the key aspects of sustainability in materials and extensively explores practices and concepts in sustainable materials engineering. Beginning with introduction and history of sustainability in materials, the chapter then discusses life cycle assessment (LCA) and stages of LCA. The application of LCA explores how the material impacts the environment, this section showcases the impacts of various materials like metals, alloys, polymers, ceramics, composites, nanomaterials, textiles, and biomaterials etc. including resource depletion, carbon footprint, energy consumption, and emissions. This chapter also includes materials recycling principles, challenges, and opportunities, providing examples of recycling metals, polymers, and composites. For further understanding of various examples of recycling and upcycling; current practices of upcycling provide insight into industrial adaptation. This chapter will be a valuable resource for educators, researchers, and industrial professionals to have an overview of sustainability in materials engineering.