Improving learning through interdisciplinary STEM has come to the forefront of educational discourse, as schools attempt to attract more students to STEM study. However, little is known about how successful STEM curricula are established and sustained. This study details the establishment and sustaining of an exemplary STEM learning ecosystem in a girls' comprehensive secondary college. Results highlight exemplary STEM ecosystems demand multidimensional principal leadership, that over time, can develop effective generative proximal processes and levels of relational trust needed to implement the disruptive reforms associated with establishing interdisciplinary STEM curricula. Findings identify principals' ongoing engagement in the environment and dispositional and developmental assets are critical to successful school change supporting STEM innovation.