The aim of this paper is to investigate the pressure exerted by supply chain partners, especially large-scale business customers and public authorities, on small- and medium-sized enterprises (SMEs) to adopt corporate social responsibility (CSR) practices. More specifically, we analyze how SME suppliers perceive and respond to supply chain pressure and then we investigate if such pressure is effective. The analysis is carried out through four case studies within SMEs in the UK. These cases are deliberately chosen to illustrate to students and CSR practitioners the potential range of different viewpoints in relation to CSR and supply chain management. The article suggests that, in order to enhance the perception of supply chain pressure as a CSR driver by SMEs, derived benefits should be more clearly identified (including moral, rational, as well as economic). There is also the risk that, when CSR requirements are imposed by large-scale business customers and public authorities, SMEs have difficulties in implementing CSR and consequently are tempted to behave opportunistically. An opportunistic behaviour can be associated to the large-scale business customers and the public authorities as well, when their commitment in CSR is perceived as only superficial. Thus there seems to be the need for a higher level of trust in such actors in order to share the potential benefits and costs related to CSR among all supply chain partners. In some cases, supply chain pressure can be detrimental to the existing initiatives voluntarily carried out by SMEs, which can consequently decrease their intrinsic motivation to engage.