Public participation procedures are frequently used by bureaucracies to involve citizens and organizations in public policymaking across countries and levels of government. CONSULTATIONEFFECTS examined whether, when, and how public participation impacts the policy inputs, processes, outputs, and outcomes of bureaucratic policymaking. The research work was organised into three streams. The first focused on the policy inputs (e.g. public comments, stakeholder feedback) entering policymaking through consultations. Using data from 1258 policy events organized in the EU, one study found that key features of policy acts subject to public comment shape the frequency and diversity of stakeholder participation in supranational policymaking. Another study found that the crafting of bureaucratic policy acts determines the information quality of public comments: informationally dense and syntactically complex acts generate comments of higher information quality. Another study, using data from 4062 Norwegian public consultations, found that a higher number of government invitations to consultations systematically correlates with higher stakeholder participation, higher diversity of interests represented, and a higher likelihood of and more frequent citizen participation. A second research stream focused on policy processes. One study showed that consultations can significantly boost the European Commission’s institutional power and leverage in negotiating interinstitutional agreements with the European Parliament and the Council. Another study showed that public participation helps the Commission preserve its reputation as a responsible policymaker and increase the likelihood that it will respond to evidence-based policy inputs. A third study examined the extent to which participatory and evidence-based policymaking can be reconciled in the design and implementation of Better Regulation frameworks. The third research stream focused on policy outputs and outcomes. One study found that participatory processes characterized by a robust representation of a stakeholder’s interests during the agenda-setting stage and consisting of more open-format participation venues systematically correlate with higher stakeholder support. Another study found that stakeholder support for the Commission’s draft legislative proposals reduces the probability of legislative amendments to those proposals. The relationship is stronger when support comes from a diverse set of stakeholders.