The quasi-market condition of education intensified the need to seek ongoing school improvements, manage uncertainty, and innovate school-wide pedagogy and curricula. Sequentially, interest in teachers' entrepreneurial behavior (TEB) has grown rapidly in recent years, which established the importance of entrepreneurial behavior as an effective response to the changing, uncertain, and increasing demanding context in the education system. However, the notion of TEB has not been clearly conceptualized or operationalized. This study attempted to offer a clear definition of TEB and identify its conceptual components. We first offered a semi-systematic literature review of entrepreneurial behavior, and then conducted a multiple-site case study at three schools in Hong Kong. We identified three competency components and three attribute components of TEB, from which we established a conceptual definition of TEB. This clarification of TEB and its components enabled the linkage to prior literature and future research.