Although practitioners have begun to implement Green IT into their companies, the governance of Green IT varies significantly. No research has been done to explain these differences in Green IT governance. Building upon contingency theory and IT governance, we develop a contingency model for Green IT governance which demonstrates the fit between contingencies and the company-specific configuration of Green IT. In the first step, three archetypes of Green IT governance reaching from centralized over federal to decentralized are presented. In the second step, we identify from literature competitive strategy, firm size, organization structure, performance strategy, environmental impact of industry, environmental strategy, IT infusion, and IT diffusion as contingency factors determining the ideal type of Green IT governance. The contingency model for Green IT governance is validated based on insights from five case studies. With the enhanced understanding of how Green IT governance is shaped by contingency factors, organizations are able to select the most successful Green IT governance form.