While corporate social responsibility (CSR) is becoming a mainstream issue for many organizations, most of the research to date addresses CSR in large businesses rather than in small- and medium-sized enterprises (SMEs), because it is too often considered a prerogative of large businesses only. The role of SMEs in an increasingly dynamic context is now being questioned, including what factors might affect their socially responsible behaviour. The goal of this paper is to make a comparison of SME and large firm CSR strategies. Furthermore, size of the firm is analyzed as a factor that influences specific choices in the CSR field, and studied by means of a sample of 3,680 Italian firms. Based on a multi-stakeholder framework, the analysis provides evidence that large firms are more likely to identify relevant stakeholders and meet their requirements through specific and formal CSR strategies.