The paper examines the role of organizational commercial slack (OCS) in mediating the relationship between entrepreneurial orientation (EO) and the effectiveness of knowledge transfer (KT) in universities. The paper identifies two types of commercial slack in the university setting: financial and promotional. Four research hypotheses are proposed. Pooled data, that is, a combination of a questionnaire survey of 110 Taiwanese universities with a data set of university KT effectiveness from the Ministry of Education, Taiwan, are collected to test the aforementioned research hypotheses. The empirical results indicate that the EO of a university enables the university to provide appropriate OCS. Furthermore, the commercial slack of a university positively mediates the relationship between EO and KT effectiveness. The paper concludes that developing EO and OCS are crucial for improving the KT effectiveness of a university. Moreover, some managerial and policy implications for promoting EO and OCS in universities are suggested.