Opportunity recognition is often an initial, but crucial step in the entrepreneurial process. However, the process of the opportunity recognition and the relationship between key factors are still ambiguous. The research question in this study is: why do some people discover innovative opportunities but not others? This research is to elaborate on the relationships between entrepreneurs' prior knowledge, information acquisition, and entrepreneurial alertness. We additionally examine the mediating role of entrepreneurial alertness. This study examines entrepreneurs in Taiwan. Participants in the study were founders who had founded new companies recently. We randomly mailed two-stages questionnaires to the entrepreneurs and 85 valid returns were obtained. Results indicate that prior knowledge and information acquisition sources had positive effects on innovativeness of opportunity recognition. Moreover, interpretation ability was both positively associated with the innovativeness of opportunities and mediated the relationship between prior knowledge and opportunity recognition. Finally, theoretical and practical implications were discussed.