This research examined the relationships among students' academic majors, levels of engagement, and learning outcomes within the context of Holland's person-environment theory of vocational and educational behavior. The study focused on the role of student engagement as a mediating agent in the relationships between academic majors and student learning. Drawing on data from a stratified random sample of 20,000 seniors who participated in the 2008 National Survey of Student Engagement, results revealed that students' academic majors were significantly related to levels of engagement and learning outcomes. Student engagement was also significantly related to learning outcomes. Students' academic majors generally were not indirectly related to learning outcomes through levels of engagement. An important exception to this result was found for students in Enterprising environments where indirect relationships among Enterprising disciplines and Enterprising learning outcomes were positive, statistically significant, and substantially larger than the direct relationship.