This paper examines the relation between formal and social-psychological elements of secondary schooling and college major selection. Students select their college major based on a "secondary sorting process" where their high school experiences are key factors that transmit certain advantages for some students and disadvantages for others. Expectations of working in a STEM occupation at age 30 are an essential catalyst for students to select a STEM major. In addition, self-efficacy in math and science influences the likelihood that a student selects a STEM major. Occupational expectations, self-efficacy, and effort completely mediate the relation between parental education and selecting a STEM major. Subject-specific indicators predicted major selection, but precollege math coursework exerted a more substantial influence in choosing a technical-quantitative major than precollege science coursework.