The environmental concerns are leading to the growing interest in the adoption of Green IS. From legitimacy perspective, this paper argues that the adoption and diffusion of Green IS among organizations are modulated by pragmatic, normative, and cultural-cognitive influences in the institutional environment. The study therefore applies topology of legitimacy to develop a taxonomy to understand actors’ strategies in shaping the understanding and development of Green IS. Using content analysis of news articles in Taiwan, the study contributes to a practical understanding of the complex institutional influences in forming the greener industry.