Although the critical role of the Internet for disseminating environmental information to achieve sustainability is widely recognized, academic research has not paid much attention to the functionality and accessibility of environmental Web sites maintained by organizations in the public or the voluntary sector. To fill this gap, the present study seeks to suggest ways in which environmental Web sites could make more effective use of the Internet's capabilities for disseminating information. This paper investigates 226 environmental Web sites, taking into account features such as orientation devices, interaction, information exchange, timeliness, accessibility and the possibility of donating online. Different types of Web sites (air, forest, water, directories) are compared and examined for signiJicant differences. The results strongly suggest that environmental Web sites have not yet fully tapped the Internet's potential, since only few environmental Web sites meet the overall technical, functional and design-related stanhrds their commercial counterparts have adopted.