This qualitative multi-case study explores the exercise and development of the design judgment of eight instructional design (ID) students working on design projects over one semester in graduate programs at four different institutions in the USA. Their design processes were explored through interviews and their design documents using the concepts of design judgment as reported by Nelson and Stolterman (The design way: Intentional change in an unpredictable world, MIT Press, Cambridge, 2012) and reflection-in-action as reported by Schön (The reflective practitioner: How professionals think in action, Basic Books, New York, 1983) to characterize the exercise and development of their design judgment across the semester. Findings reveal that these ID students make multiple design judgments concurrently and constantly. Their prior design experience, the course requirements and their design practice in class influence both the exercise and development of their design judgment. Lastly, the development of their design judgment is both perceptible and personal. In light of these findings, recommendations are made for how to support the development of ID students' design judgment.