Claims as to how participation improves environmental governance are legion, as are sceptical contributions challenging the value of participation. Different fields of study have made a variety of arguments on the pros and cons of participation and its efficacy in producing environmentally beneficial outcomes. Participation of non-state actors in public decision-making captures a wide variety of governance modes and 'degrees' of participation, such as round tables, web-based consultation or citizen fora. Including environmental concerns in participatory governance structures is expected to benefit the environmental substance of decisions. Stakeholders may hold local knowledge that is more accurate than knowledge normally available to decision-makers. Scientific models may simply be wrong or inadequate if they fail to take account of local conditions. Participatory governance can provide decision-makers and participants with information, and build individual and collective capacities that aid implementation and compliance. Networks of stakeholders potentially mobilise collectively held knowledge and capacities in ways that are appropriate to and supportive of implementation.