Despite increasing emphasis on the adoption of IT targeted at reducing adverse environmental impact of organizations’ operations, referred to as green IT, or sustainable IT, there is a lack of empirical research that investigates the impact of different sustainable IT practices on environmental performance. By drawing on past research on the types of sustainable IT practices (defined in terms of “information to support decision-making”, “direct IT assets and infrastructure”, “collaboration” and “sustainable products and services”, and the resource based theory of IT and IT assets classes, we examine the relationship between sustainable IT practices and environmental performance (defined in terms of direct and indirect emissions). Drawing from a secondary database of 223 observations from 47 sustainable IT organizations, we test our hypotheses and find that different sustainable IT practices affect environmental performance differently. Specifically, “information to support decision making” reduces direct emissions while “direct IT assets and infrastructure” reduce both direct and indirect emissions. “Collaboration” does not have any positive environmental impact. “Sustainable products and services” reduce indirect emissions but not direct emissions. Implications for research and practice are discussed.