The mainstream scholarship assessing EU external action frames the subject in terms of success or failure to achieve the intended effects, the latter generally defined against the EU's own stated objectives. Resting on a tacit assumption that EU engagement in third states is a good thing, these analyses are framed as ‘positive impact or no impact’ and tend to neglect the wider effects of EU policies. This article maintains that EU external action may and often does have unintended consequences, thus expanding the study of EU impact beyond the sheer study of EU effectiveness. Drawing on broader literature on unintended consequences, the article proposes a framework for analyzing unintended consequences of EU external action. It synthesizes and adapts to the EU context a classification of unintended consequences and, in order to illustrate its utility, applies the proposed framework to three empirical examples derived from EU neighbourhood, migration and trade policies.