Although teachers' learning has been increasingly recognised as nonlinear and contextually responsive, few studies have extended these understandings to the design and evaluation of professional development. In this case study, we examine nonlinear and contextual manifestations of high school science teachers' professional learning from a complex systems perspective. At a summer institute, we surveyed 22 teachers over eight days using a modified form of the Pedagogical Discontentment scale, and modelled the valence and salience of beliefs about learning, teaching goals, instructional self-efficacy, and intentions for practice using multidimensional scaling analysis. The analysis revealed cohort-level fluctuations in the psychological salience and relative overlap and separation among constructs that mirrored the particular daily foci of the institute. We consider theoretical and practical implications of adopting a complex systems approach to the design and evaluation of teacher professional development.