Higher education has increasingly been called upon to develop interdisciplinary programs -- particularly in STEM fields -- that prepare students to address multi-faceted, real world problems. While the tensions between disciplinary cultures and interdisciplinary programs have been previously studied, relatively little is known about the experiences of students in interdisciplinary programs. In this grounded theory study, we interviewed 45 STEM students and alumnx from an interdisciplinary program at a public research institution to examine how individuals understand and integrate interdisciplinary perspectives into their academic pathways. Our findings demonstrate that participants moved through stages of interdisciplinarity regarding choice, navigation, and integration.