This study explores why and how firms respond to social demands through philanthropic giving in the context of a severe natural disaster. Drawing on Marquis and Qian's organizational response model to government signals, we integrate resource dependence theory and institutional theory to build a two‐step model of organizational response to social needs, in situations of disaster relief. We argue that firms depending more on the government for support are more likely to donate in disaster relief, while firms who receive more scrutiny from the government and the general public and firms having more slack resources are likely to donate more. Evidence from Chinese listed companies' donations to the 2008 Sichuan earthquake largely supports our predictions. This study provides a more precise understanding of the corporate philanthropic decision process, decoupling the drivers of philanthropic giving, and those determining the amount given. Theoretical and practical implications are suggested.