The first steps in using internet as a legitimate channel for public participation in environmental impact assessment (EIA) in Portugal occurred on the occasion of the Valorsul proposed incinerator for urban solid waste. Supported by IPAMB and other agencies of the Environmental Ministry, CITIDEP put forward the IMS Project (Intelligent Multimedia System in support of expert review and public participation). A multimedia system prototype (IMS) was used and tested together with the Internet during the official period of public participation. IMS was also essayed with students from undergraduate programs (Environmental Engineering at the New University of Lisbon and Psychology at the University of Lisbon), as part of practical course work. In this paper we describe key components of the experiment and discuss some of its results (which include some expected and unexpected obstacles and positive performances), concerning the role of this technology for different kinds of audiences and actors, and the regulatory and institutional context. Supported by this results, we argue that regulatory framework and institutional culture is the "hard part" of the equation PPIT. We contend that internet-based exchange of information on EIA cases should be promoted and indeed mandatory to the extent allowed by existing technology, as it has proved to play an irreplaceable role in active public participation.