This paper argues for the centrality of expression for the project of phenomenology. It shows, first, that the concept of expression grows out of the debate with Frege concerning meaning that led to Husserl's distinct phenomenological project. Specifically, expression is Husserl's first attempt to more rigorously define 'sense" as the essential connection between subjective acts of meaning and "objective" meanings. This account of expression is then taken up in Husserl's later work on spirit, which thereby makes expression central to Husserl's entire analysis of the lifeworld. Insofar as Husserl saw phenomenology growing out of his dispute with Frege on meaning, and working toward the ability to clarify the sense of all scientific knowledge, expression names the promise inherent to phenomenology itself, that which defines the very project of phenomenology.