The complex of problems suggested by the term life-world pervades contemporary thought, even though such a complex is rarely called by this name [...] Time does not allow us, however, to perform an extensive review of the secondary literature on the 'Crisis'. I will only suggest that a survey of this literature, especially the works of Brand, Merleau-Ponty and Habermas, presents us with a dilemma. It seems that there is a difficulty in Husserl's characterization of the life-world. On the one hand, it is understood as the plurality of individually different socio-cultural environments and thus the result of an historical development; on the other hand, it is interpreted as a single structural basis common to all environments and thus an a priori for that history through which they become different. This dilemma concerning the content of Husserl's theory is coupled with a problem having to do with the method of his analysis: how is Husserl's procedure of phenomenological reflection upon a transcendental ego or "monad" able to account for the intersubjective life-world in either of the senses just sketched? Putting the question in this fashion is usually the first step on the way to abandoning a transcendental account of historicity, or, as is the case with Habermas, replacing the transcendental ego with a community of language users. What I want to propose in this essay is precisely what current thinkers seem unanimous in rejecting. I want to argue for a transcendental theory of the life-world and of historicity, and I want to do so by suggesting that a phenomenological reflection upon the transcendental ego - once correctly understood - is the proper procedure for constructing such a theory. In this paper I will discuss such a theory by undertaking a brief study of Husserl's concept of the life-world and by isolating several difficulties which I detect (Part I). I will then introduce a theory of the transcendental reduction as the key to resolving the difficulties I discover (Part II). Finally, I will undertake my own systematic analysis of the a priori of the life-world and will suggest a way of integrating such an analysis with what I will call a transcendental history of the experience of consciousness (Part III).