This chapter comprehensively describes social aspects and social sustainability in a circular plastics economy and especially how to measure social impacts within a circular plastics economy and beyond. For this purpose, a brief introduction to social aspects and sustainability is given. After that, two distinct methods are presented, which are used to assess social aspects and social sustainability in general and with a dedicated focus on a circular plastics economy. The first method is the so-called social life cycle assessment. The second method is the sustainable development goals–based assessment. A brief how-to guide is presented for social life cycle assessment, enabling practitioners to conquer the four phases of social life cycle assessments. For the sustainable development goals–based assessment, the approach is presented according to its five steps. Next, a case study introduces how to showcase sustainable development goals–based assessment to the example of closed-loop textiles recycling within a circular plastics economy.