The purpose of this study is to analyze the influence of Corporate Social Responsibility (CSR) on a firms’ sales growth and to assess the mediating role of competitive advantage and the moderating role of the employee’s individual belief of social responsibility (SR) on the relationship between CSR and sales growth of small and medium enterprises. A survey of 107 small and medium enterprises (SMEs) in the consumption and manufacturing industry of a developing country was performed. Structural equation modeling based on AMOS path was employed to test the hypotheses linked to the relationship between CSR and sales growth of SMEs. Results indicate that the link between CSR and sales growth is mediated through competitive advantage and that the positive impact of CSR on sales growth is moderated by the employee’s individual belief of social responsibility.