Conceptual change in undergraduate capstone courses provides unique opportunities to examine how students draw from multiple courses and experiences to resolve conceptual confusion. We examined how senior-level natural resource management students revised their conceptions of 'ecosystem' throughout their capstone course. The concept of ecosystem is complicated by a lack of shared meaning across disciplines. Our grounded theory study analyzed student coursework and pre/post interviews. It was informed by socio-cultural and conceptual change theories and used an ecological literacy metric to examine how students' conceptualizations of the relationships between natural, ecosystem, human, and human artifact influenced their conceptions of ecosystems. Students who did not describe ecosystems as natural struggled less with integrating human society into ecosystems than their peers that did. We conclude that it is important to explicitly create shared meaning of key conceptions at the start of a capstone course to facilitate shared meaning-making and desired conceptual change during the course.