Over the past decade, the inclusion of citizens in political decision-making through electronic participation (e-participation) has received much attention. Many projects have been, and are continued to be executed at different levels of government. E-participation projects aim at providing a facilitating online environment, where citizens and other relevant actors can be involved in the processes of public decision-making. Up to now, the evaluation of the success and impact of such projects has not been addressed widely in research. This paper studies existing evaluation approaches and details the EF³-framework, which was developed to assess effectiveness, efficacy and efficiency of e-participation experiences. The EF³-framework has been reviewed, revised and applied to the e-cognocracy real-life experience of the municipality of Cadrete (Zaragoza) to provide a proof of concept for assessing impact of e-participation via the EF³-framework. Also, the EF³ framework has been validated by international experts, who also assigned weights to individual indicators for each of the three criteria. The revised model with details of indicators, the proof of concept of Cadrete, and the results of expert reviews and assignments of weights to criteria are summarised in this paper.