Efforts to assess the effectiveness of environmental law through legal indicators are indispensable at a time when environmental law and its effective implementation and enforcement are crucial in the global  transformation towards a sustainable society. Environmental law requires tools which allow governments and society in general to accurately measure and inform about the extent to which the law is being correctly and effectively applied. Environmental legal indicators, with their corresponding methodological compliance steps, provide this needed accuracy to measure the effectiveness of the law. This publication draws together legal ideas presented at the 2nd World Environmental Law Congress European (December 2021) and showcases ongoing work on environmental legal indicators carried out by WCEL and its partners.