“Green” supply chain management (GSCM) has often been associated with highly visible companies (Bowen, 2000) and firms within consumer-focused industries (Buysse & Verbeke, 2003; Hall, 2000; Roht-Arriaza, 1996). As such, GSCM has partly been led by development of consumer awareness of environmental issues (Beamon, 1999; Zhu et al., 2005). This suggest that firms operating in business-to-consumer (B2C) markets have strong incentives to implement GSCM, due to both institutional and stakeholder pressure. However, this leaves the role of GSCM in business-to-business (B2B) sectors relatively unexplored and to-date little is known about: 1) the relative engagement with GSCM among firms in business-to-consumer and business-to-business sectors; 2) the conditions that are necessary for successful implementation of “green” practices in B2B supply chains. This study addresses these issues within the context of 340 buyer–supplier relationships in the United Kingdom, using an innovative research methodology that captures firms' engagement with GSCM practices and minimizes social desirability and common source biases. Our results show that GSCM is relatively limited among firms in B2B markets compared to firms in B2C markets. At the same time, we show that developing trust with supply chain partners, while also having top management support, is a crucial driver of engagement with GSCM among firms in B2B sector but less important among firms in B2C sector. These findings provide considerable insights to managers and marketers of B2B supply chains that seek to respond to a growing interest of environmental performance of supply chain.