There are many barriers to the implementation of new practice standards. To implement practices that both prepare and inspire their students, preservice teachers need opportunities to enact reform practices: to prepare and be inspired themselves. These opportunities are found in students' content courses, methods courses, and field placements. In this article, we interrogate the barriers and supports for implementing reform-based STEM (science, technology, engineering, and mathematics) practices at the end of preservice teachers' methods courses. Students who have access to reform practices in all three learning contexts are most likely to be prepared to prepare and inspire their future students, whereas other students may actively resist STEM disciplinary practices, possibly because they have had fewer opportunities to experience such practices themselves in both K-12 and higher education classrooms. The weak link for our students provides focus for future work: Almost all students lacked in their ability to design for disciplinary practices.