Environmental consultants act as intermediaries between clients (public and private sector) and stakeholders (both statutory and non-statutory), presenting information and arguments on behalf of clients to stakeholders and gathering stakeholders' views. This research explores environmental consultants' perceptions of the processes of consultation about air quality issues with a view to analysing their role in the process and the tensions they face. The study used a mixed-methods approach: a survey of 150 environmental consultants, two focus groups and three in-depth semi-structured interviews. The results show that consultants are conservative in their choice of consultation methods, choosing approaches that minimise the risk to clients' desired outcomes. Resource and time constraints further limit the scope of many consultations. Consultants typically make little effort to evaluate the consultation process, relying on outcome measures (such as a successful planning application) and process measures (numbers attending meetings) rather than considering the outcome in relation to participants. However, environmental consultants were aware of issues such as raising the expectations of participants and the need to be transparent about the extent to which participants can influence decisions. Given the widespread use of environmental consultants to manage the consultation process, the research raises questions about the purpose of consultation (is it to improve outcomes, to comply with regulations or to build consensus?). © 2012 Copyright Taylor and Francis Group, LLC.