The purpose of this study is to revisit the widely held assumption that the impact of socioeconomic background declines steadily across educational transitions, particularly at the postsecondary level. Sequential logit modeling, a staple methodological approach for estimating the relative impact of SES across educational stages, is applied to a nationally representative cohort of high school sophomores drawn from the National Center for Education Statistics' Education Longitudinal Study of 2002. However, the study extends the traditional sequential logit approach by examining how socioeconomic background interacts with students' academic ability and postsecondary institutional selectivity and how the nature of these interactions varies across postsecondary stages. Analyzing the interactions between these three resources (socioeconomic, academic, and institutional) reveals the need for a more nuanced understanding of how SES influences students' postsecondary outcomes. This new approach is termed the Postsecondary Resource Trinity Model. The empirical results and conceptual model have important implications for the way in which policymakers and higher education practitioners promote the postsecondary success of disadvantaged students, as well as for how scholars of higher education and social mobility study the relationship between socioeconomic background and postsecondary outcomes.