Traditional environmental policy instruments have not always proven successful in fostering environmentally friendly behaviour. The question remains: how can policymakers tackle the attitude-behaviour gap when it comes to pro- environmental choices and sustainable lifestyles? One solution that has emerged is green nudging, a new and potentially promising policy tool born of behavioural economics and experimental psychology. This paper contributes to the current discussion surrounding green nudging with an extensive overview of the subject and the establishment of a policy evaluative framework, which, in addition to incorporating the criteria, efficacy and effectiveness, focuses on the commonly neglected dimension of ethics. A preliminary policy evaluation of two types of nudging — defaults and social norms — suggests that while green nudging has proven to be both efficacious in laboratory settings and effective in real life, there remain many ethical concerns that must be accounted for in the implementation of this new policy instrument. Policymakers may be able to use these insights to further develop green nudging as a means to promote pro- environmental behaviour and come a step closer to effective and ethical environmental policymaking.