This paper presents a review and assessment of existing theoretical accounts to explain differentials in access to education and training in advanced economies. These theories tend to focus on the analysis of the influence of a set of economic, sociological and political variables on access to education. Existing theories are criticized on two grounds. Firstly, they seldom take into consideration the crucial role of political-institutional factors, and in particular, welfare states' actions through direct investment and regulation in shaping access levels. Secondly, they focus narrowly on the analysis of different stages of education and training, and this does not reflect the current policy emphasis on lifelong learning. The paper concludes with an outline of a future research agenda to address these gaps, and also calls for a more rigorous analysis of the weight of the different factors affecting access.