Ever since Thaler and Sunstein published their influential Nudge, the book and the theory it presents have received great praise and opposition. Nudge-theory, and more particularly, nudging may be considered an additional strategy providing some novel instruments to the already rich governance toolbox. But what is its value? The current debates on Nudge-theory are often highly normative or ideologically driven and pay limited attention to more practical aspects of the theory: Whether and how is nudging evaluable as a theory and a practice? Whether there is solid evidence available of nudge success over other governance interventions? What is to be considered a nudge success at all? What data and evaluative techniques may assist in evaluating nudging beyond individual cases? The current article seeks to explore these questions.