Background: Engineering education scholars (EES) seek to advance innovation, excellence, and access within education systems and the engineering profession. To advance such efforts, the intentional and strategic actions taken by scholars must be better understood. Purpose/Hypothesis: This study aimed to advance the field's understanding of agency toward impact by (1) closely examining the experiences of early career EES pursuing impact in engineering education and (2) co-constructing a contextualized theory of agency. We define agency as taking strategic actions or perspectives toward professional goals that matter to oneself and goals that relate to impacting engineering education. Design/Method: Building on previous work about faculty agency, we leveraged approaches from grounded theory and integrated multiple qualitative approaches to analyze our experiences as six early career EES over the course of a 4-year longitudinal study. Results: Seven key insights about the professional agency toward impact in engineering education of early career EES emerged from the analysis. The contextualized theory and resulting visual representation illustrate this agency as a cyclical process with three components: (1) the factors influencing one's agency, (2) the agentic process itself, and (3) the output of the agentic process. Conclusions: Our co-constructed contextualized theory extends previous work by incorporating the temporal nature of agency, the generation and assessment of available moves, and the importance of feedback on future agentic practices. Our results have implications on how the engineering education community supports graduate students, early career scholars, and new members in their efforts to impact change.