Background/Context: As concerns mount about the shortage of students entering science, technology, engineering, and math (STEM) careers, policy makers throughout the United States are contemplating strategies to maintain and enhance our nation's economic vitality and international competitiveness. Within this policy and program environment, researchers have focused considerable attention on improving STEM education at different stages of the educational pipeline, yet we lack evidence on how resources from one educational setting may influence outcomes in a successive educational setting. Purpose/Objective/Research Question/Focus: The purpose of the study is to examine individual- and school-level factors that influence students' pathways to the STEM fields during college. Focusing on the importance of high school-to-college linkages, our research questions address the individual and institutional factors that affect students' likelihoods of majoring in a STEM field in college. Research Design: The study is based on data collected through the Educational Longitudinal Study of 2002, a nationally representative survey of high school sophomores who were followed through high school and into college. Students who were enrolled in a four-year institution at the end of 2006 and had declared a major were included in the analytic sample. Analysis: In addition to performing descriptive and factor analyses, we used cross-classified hierarchical general linear modeling to examine students' backgrounds, aptitudes, attitudes, dispositions, and experiences in relation to majoring in a STEM field, as well as institutional factors that constitute students' secondary and postsecondary environments. Findings/Conclusions: Findings from the study revealed significant effects in relation to race, academic preparation, attitudes and dispositions toward math and science, college choice considerations, and postsecondary experiences. Although no institutional effects were uncovered at the high school level, both postsecondary sector and selectivity significantly influenced propensities toward majoring in a STEM discipline. The study concludes with several policy recommendations related to K-16 collaborations, dual-enrollment programs, and developmental considerations for teachers and counselors working with high school students.