The thesis that truth is a logical notion has been stated repeatedly by deflationists in philosophical discussions on the nature of truth. But what is a logical notion? Building on Tarski (1986) several authors have discussed and developed the idea that the characteristic generality of logic can be turned into a criterion of logicality based on the invariance of the symbols' interpretations under large classes of transformations on the domain. In this paper, we show how the deflationist can use invariance criteria in support of her claim that deflationary truth is a logical notion.