“Opportunity” is a word that has appeared frequently in the entrepreneurship literature. However, scholars have approached entrepreneurial opportunity and the process of perceiving opportunities, from a variety of diverse perspectives. This has led to inconsistent and apparently contradictory theoretic models and empirical findings, and more fundamentally, to inconsistent definitions and operationalizations. It sometimes seems that the only thing scholars agree upon with regard to opportunity is the spelling of the word. Thus much of the work done by scholars on entrepreneurial opportunities and opportunity perception can not be generalized to our understanding of the concepts. Theory building is frustrated by the fact that these scholars were not all examining the same theoretic constructs. To shed some light on the issue, we examined the various theoretic and operational definitions of entrepreneurial opportunity and opportunity perception used by scholars and compare and contrast those definitions in light of the theoretic perspective driving each study.