Since the early 1970s, many jurisdictions have broadened legal standing rules to encourage environmental citizen suits and improve compliance with public rights. Although now widely adopted, expanded standing provisions are frequently criticised on the grounds they can give rise to significant social costs. This article sheds light on the costs associated with expanded standing provisions by evaluating the impacts of citizen suits taken under the Australian Government’s principal environmental statute, the Environment Protection and Biodiversity Conservation Act 1999 (Cth). The results suggest the social costs of citizen suit activity under the Act over the period 2000–2015 were negligible. Environmental citizen suits were seldom taken and rarely won; the substantive effects of successful suits were often nullified by subsequent executive action; and the suits generally had negligible or minor effects on project timelines