Local supplier corporate social responsibility in developing countries represents a powerful tool to improve labour conditions. This paper pursues an inter-organizational network approach to the global value chain literature to understand the influence of suppliers’ collective behaviour on their CSR engagement. This exploratory study of 30 export-oriented and first-tier apparel suppliers in Bangladesh, a developing country, makes three relevant contributions to GVC scholarship. First, we show that suppliers are interlinked in a horizontal network that restricts unilateral CSR engagement. This is (...) justified in that unilateral CSR engagement is a source of heterogeneity in labour practices; consequently, it triggers worker unrest. Second, we present and discuss an exploratory framework based on four scenarios of how suppliers currently engage in CSR given their network’s pressure toward collective behaviour: unofficial CSR engagement, geographic isolation, size and competitive differentiation, and external pressure. Finally, we show the need to spread CSR homogeneously among suppliers and to reconceptualize the meaning of CSR in developing countries, encouraging more scrutiny toward horizontal dynamics. (shrink)