Despite the frequent association of circular economy (CE) with sustainability, most CE practices have yet to prove they actually contribute to achieving the Sustainable Development Goals (SDGs), and social aspects in particular. To attain the consensually established targets in the SDG framework, it is vital to assess the impact of CE practices. As most of these practices are carried out in a network of actors, sustainability assessment approaches from the fields of industrial ecology and supply chain management are particularly suitable. However, both fields are known for their limited inclusion of the social dimension. While scholars have already started to explore the assessment of social sustainability within the context of CE practices, little is known about the perspectives and experiences concerning social assessment of businesses actively involved with CE. Thus, the authors conducted 43 semi-structured interviews with frontrunner companies engaged with CE in Italy and the Netherlands to obtain a better picture of (1) how these firms view the importance of the social dimension as part of the assessment of CE practices, (2) what the barriers to conducting social assessment are, and (3) whether they have experience with assessing social sustainability aspects within their companies and supply chains. Through a thematic analysis, it was found that most companies deem the social dimension to be relevant to CE assessment and either consider it an integral part of CE or of sustainability. However, a majority of the firms did not conduct any type of social assessment. Most companies which implemented assessments did so in a qualitative manner or used industry-based sustainability indicator frameworks. Notwithstanding the prevalence of social life cycle assessment in the academic realm, almost all interviewees mentioned barriers to its application related to its complexity and the lack of a standardised approach.