Citizen engagement in policymaking represents an increasingly popular mechanism for both civic rejuvenation and environmental policy innovation. Its application in many different policy fora from city budgeting to housing and energy systems across various national contexts provides, in theory, space for the public to feel empowered, connected to new policy spaces and positions them to aid in design and implementation of more effective solutions to complex social and environmental problems. This engagement takes many different forms, including deliberative polling, citizen's assemblies, online referenda and creation of community-based ownership. However, various forms of engagement are also accompanied by challenges of poor design and limited local capacity that can undermine their effectiveness and, ultimately, public confidence in government actors and processes. This article challenges renewable energy advocates to consider more serious insights from political and institutional theorists about the complexities of participatory designs. It draws on three initiatives in Canada and Denmark to illustrate both the promise and the challenge of public engagement in this significant policy subsector.