We propose the periodic retrospective assessment (PRA) technique for reflection-based evaluation of interdisciplinary, team-oriented learning experiences. PRA is characterized by two forms: an assessment at the end of each production iteration, followed by a summative assessment after production has ended. An empirical evaluation of PRA was conducted within a fifteen-week immersive studio-a student-driven, faculty-mentored learning experience in which all learner activity is directed toward a single project, undertaken in collaboration with a community partner. This evaluation reveals that students maintain primary focus on pragmatic production issues during the studio duration, although with secondary yet consistent focus on learning and development. PRA surfaces how the immersive studio produced positive learning outcomes with respect to interdisciplinary collaboration and lifetime learning.