This paper examines market scoping for early stage technologies, a fundamental yet underexplored marketing activity. Market scoping refers to managerial activities directed at the identification of market spaces for early stage technologies. Our discovery-oriented research aimed at theory development draws on an extensive, multi-year database of email trails and archival records detailing market scoping efforts for early stage technologies emerging from a global research university. Based on this longitudinal database, we provide an in-depth examination of managers’ market space decisions and advance an initial theory of market scoping. We isolate managers’ market scoping mindset—which manifests as market ambiguity avoidance or acceptance—as a key explanatory construct shaping market space decisions and outcomes. Market ambiguity avoidance results in managers’ downstream orientation toward end-users; this mindset, counterintuitively, may lead to technology commercialization failure. In contrast, market ambiguity acceptance results in managers’ upstream orientation; this mindset directs attention away from end-users, but helps uncover indirect paths to viable market spaces. This paper lays the groundwork for advancing marketing research in the context of early stage technology commercialization.