AbstractResearch on social sustainability in multi‐tier supply chains is limited. Specifically, we know very little about a) the micro‐processes involved in the way in which sub‐suppliers (i.e., first‐tier suppliers or sourcing agents) respond to the sustainability requirements imposed by their intermediaries; and b) the micro‐level antecedents that condition their responses. To address these gaps, we used a longitudinal multiple case study method to explore multiple intermediary – sub‐supplier dyads in South India's knitwear garment industry and drew upon constructs of behavioural economics. We found that the way in which intermediaries frame social sustainability requirements and their associated procedures influence both the way in which sub‐suppliers perceive the procedural fairness of those requirements and the way in which they thus reciprocate. When intermediaries frame social sustainability requirements as ‘opportunity’ and engage in various procedures perceived to be procedurally fair by sub‐suppliers, the latter reciprocate positively. Contrastingly, when intermediaries frame social sustainability requirements as ‘insulation’ and engage in various procedures perceived to be procedurally unfair by sub‐suppliers, the latter reciprocate negatively. Under the production‐dominant framing, sub‐suppliers exhibit positive reciprocity only related to processing production orders. Our analysis inductively generated propositions that emphasize the important role played by framing in shaping the perceptions of fairness held by sub‐suppliers towards social sustainability requirements and the reciprocity of the latter's responses to them.

Forced labour poses a significant challenge within global supply chains, yet traditional compliance-based governance based on auditing has proven to be ineffective in addressing this issue. Non-government organizations and worker rights organizations can serve as crucial allies in supporting and safeguarding workers by assuming the role of a 'social intermediary' (SI) between supply chain firms and workers. However, these external organizations often hold limited power within these supply chains. In our paper, we examine the sources of power that SIs can cultivate and utilize to lead successful interventions against forced labour in supply chains. Through a comparative case study involving three SIs and their collaborative efforts with a global seafood brand, we explore various forms of non-mediated power and their underlying origins. By establishing these connections, we shed light on the effectiveness (or lack thereof) of interventions against forced labour. Our research makes three contributions. First, we contribute to ongoing research on forced labour in supply chains by emphasizing the constructive role that SIs can play to protect vulnerable workers. Second, we address a critical gap in the existing literature concerning power of SIs in supply chain relations. More specifically, we specify sources and types of non-mediated power that SI can leverage to design effective interventions against forced labour. Third, by comparing unique data on two worker groups vulnerable to forced labour – vessel workers and workers in seafood processing – we provide much-needed insights into how working conditions in non-factory settings can still be regulated.