Disruptions to education systems (e.g., the COVID-19 pandemic) evoke a range of responses from teachers. Teachers are required to learn new skills, attend to students' social emotional needs, modify their instructional approaches, and discover innovative ways to engage their students in science, technology, and engineering courses, all while managing their own professional and personal needs. Although teachers of all disciplines adjust their instructional and curricular approaches in response to disruptions, the impetus for this study was to explore the unique challenges of science teachers during the COVID-19 pandemic that affected their sense of agency (sense of control). To understand how science teachers acquired, used, and invested in capital (i.e., available resources with the potential to meet identified challenges) to achieve professional agency, we studied 113 science teachers in 2020-2021 when they experienced disruptions associated with the pandemic. An analysis of open-ended responses from 60 teachers indicates that teachers who achieved agency shared four attributes. They: (1) demonstrated an awareness of needed capital, (2) acquired capital, (3) used capital, and (4) dedicated effort toward capital-building for future use. Our findings inform science teacher educators and schools that are committed to mitigating science teacher attrition by understanding how teachers respond to personal and professional stresses.