Background/Context: In the last several decades, a college education, in particular the bachelor's degree, has become the key to higher earnings, and overall, to a middle-class lifestyle in the United States. In an increasingly globalized economy, privileging information and communication technologies, it is more than likely that this emphasis on higher education in the American labor market will continue in the future. While we know much about the increasing link between a college education and social mobility, writ large, we know considerably less about who actually makes the transition to college, how this occurs, and why. Despite the strides made, large numbers of individuals are not making the transition to college. Among those who are, there are important differences in the kinds of postsecondary institutions they are attending, and in completion rates, with attendant implications for social mobility. Purpose: This article has two purposes: (1) to synthesize the key facets of our knowledge base of how to expand the college pipeline and relatedly, to outline particular areas that have been under-examined across the disciplines; (2) to provide future directions that will allow us to better address this important inquiry along substantive and methodological lines. Research Design: This article draws on disciplinary papers commissioned by the Social Science Research Council's Transitions to College Committee. The discussion of preparation is framed around the contributions from the fields of anthropology, and political science; access vis-à-vis history, sociology, and demography; paying for college vis-à-vis economics; and completion vis-à-vis the field of higher education. Conclusions/Recommendations: The article calls for an overall integrative model, e.g., K-16 and interdisciplinary, improved coverage in large-scale datasets, and a more refined mixed methods approach to attend to notable gaps in our understandings of the transition to college. Across disciplines, a key substantive gap is variation along the lines of race, ethnicity, immigrant status, gender, and age across domains, which needs to be illuminated. [ABSTRACT FROM AUTHOR]