Because of ambiguous theorizing and the dearth of agreed-upon methodologies, previous research on the imagination and assessment of emergent ?new venture ideas? / ?opportunity ideas? has tended to confound the perceived qualities of the idea itself with the evaluator?s ability and motivation to act on it. To address this important shortcoming, we develop and test a short and easy-to-use survey instrument designed to measure third-person opportunity confidence (OC), defined as the result of an actor?s evaluation of a new venture idea as a basis for the creation of new economic activity, independent of his or her own abilities and/or motivation to act on this idea. Drawing from five empirical studies conducted with entrepreneur and general population samples, we find that our OC measures meet the criteria for content, discriminant, and criterion validity and show high levels of internal consistency, inter-rater and temporal reliability. The instrument? flexibility, shortness and broad contextual applicability further reinforce its potential for future research. We conclude by discussing how the measure could be applied in several important types of entrepreneurship study.