["Business Strategy and the Environment, Volume 35, Issue 5, Page 6304-6320, July 2026. ", "\nABSTRACT\nImpact measurement is crucial for sustainable ventures to quantify their contribution to sustainable development. Although research has highly focused on impact measurement as a static activity, we conduct a qualitative study to explore how impact measuring as a process unfolds over time. Our analysis reveals that sustainable ventures move along three impact measuring trajectories, which we label reactive, proactive, and agentic impact measuring. Each trajectory results in distinct positions of impact within the value proposition of the sustainable venture. Thus, we propose a novel process perspective on impact measuring, unveiling the role of agency along different impact measuring trajectories and uncovering the relationship between impact measurement and the value proposition in sustainable business models.\n"]