While opportunity beliefs, specifically the confidence in the viability of a new venture idea, are recognised as key drivers of entrepreneurial processes, the mechanisms through which they function remain unclear. We hypothesise that individuals adjust their opportunity confidence according to the valence of external assessments, with this effect amplified when the assessment comes from a prestigious source. Furthermore, we hypothesise that lower levels of opportunity confidence subsequently motivate efforts to revise the new venture idea. In two vignette experiments, we find empirical support for our hypotheses. In so doing, we offer insights into the cognitive mechanism through which assessment can motivate efforts to revise the content of new venture ideas as a way to (re)direct the entrepreneurial processes.