In the sustainable supply chain management literature, the social dimension has been insufficiently investigated. The aim of this research is to analyze why and how focal companies implement and manage social sustainability in their supply chains. To do this, we adopted a multiple case study research strategy in six focal companies which had implemented 34 supply chain social initiatives. We draw from the constructs of motivation and supply chain engagement to develop a typology that improves our understanding of the complex interactions between the management of supply chains and their social sustainability performance. This research also explored a third concept, social relationship level, which helps us to understand which relationship levels focal companies often use to operationalize such initiatives. Results suggest that intrinsically motivated social sustainability initiatives in supply chains led focal companies to adopt supply chain structural collaborations, while extrinsically motivated social initiatives were more strongly connected with information exchange only. The involvement of primary stakeholder groups (e.g., consumers and suppliers) occurs usually in extrinsically motivated social initiatives, while the involvement of secondary stakeholders (e.g., NGOs and community) seems to be the norm for intrinsically motivated social initiatives.