Built on the categorization theory and Herzberg's dual‐factor theory, this study consisted of two experiments to investigate how and when small brands were affected by the corporate social responsibility (CSR) performance of other brands in the same product category. This study specifically focused on the type of CSR publicity (positive vs. negative), brand fit (high vs. low), and other brands' leadership positions (high vs. low). The results of Study 1 (156 U.S. consumers) revealed that a leading brand's CSR activities can increase consumers' CSR expectations toward another big brand more than that toward a small brand, by setting up consumers' CSR expectation standards toward the industry as a whole. That is, the big brand's CSR performance was less likely to increase CSR expectations toward the small brand. Study 2 (244 U.S. consumers) confirmed that a brand's CSR activities positively influence its product attitude. In addition, the effect of a small brand's negative CSR publicity on its product attitude was mitigated by other brands' similar publicity. In contrast, other brands' publicity did not amplify the effect of a small brand's positive CSR publicity. These findings manifested small brands were conditionally influenced by other brands in the same category. This suggested that small brands should strategically allocate resources to fulfill CSR by determining their position relative to leading brands as well as to other players in the market.