The chapter offers a systematic overview of the use of digital tools for various forms of political participation and the experiences made so far, based on an extensive literature review. Discerning three key functions of e-participationmonitoring, agenda-setting and input to decision-making-the authors review a variety of formally institutionalised mechanisms as well as informal expressions of civic engagement, including social media. The examination of digital tool use for monitoring purposes extends from electronic information access and exchange to e-deliberation, while the role for agenda-setting mainly includes uses for e-petitions and e-campaigning, showing a mixed picture of democratic impacts. The review of e-participation providing input for decision-making focusses on e-consultations, e-participative budgeting and e-voting, identifying several persisting problems with the latter instrument. A special section examines e-participation at EU-level, from deliberative citizens' involvement projects and e-consultation to the European Citizens' Initiative (ECI) and e-petitions to the European Parliament. Findings show that digital tools enhance direct and participative democracy in many respects; however, exaggerated expectations of new democratic potentials remain unfulfilled: deliberative participative designs lack any impact on decision-making, and the ECI still is rather an instrument for civil society mobilisation than citizen empowerment. 4.1 Three Basic Functions of e-Participation Understanding "e-participation" as the use of digital tools for political participation in the wider sense includes a wide variety of formally institutionalised mechanisms, as well as informal expressions of civic engagement. According to their predominant function in the policy cycle, we can discern three basic functions of participation (we prefer this typology because of the focus on level of impacts):