This article engages critically with the theory of expression proposed by Mitchell S. Green in his Self-Expression (2007). In this book, Green argues that expressions are signals designed to convey information about mental states. By putting pressure on one of the examples Green uses in his book, I will challenge this thesis. I will then deepen this challenge by developing a contrast between two philosophical perspectives on expression, which I name the 'instrumental' and the 'descriptive'. I take Green’s theory of expression to be an exemplar of the instrumental perspective. Expression, in the instrumental perspective, is a means for transmitting information about mental states from organism to organism. The descriptive perspective I articulate with the help of Maurice Merleau-Ponty and Ludwig Wittgenstein. On the descriptive view, expression is (at least a part of) an answer to the question what it is so much as to have mental states and a living body. I suggest at the end of the article that if we remain within the instrumental perspective, we will not be able to use expression to satisfactorily answer this question.