Using a sample of 7,260 university employees, we investigate how legitimacy, social and human capital influence the employees’ start-up propensity. We find that scientific legitimacy, as measured by the number of recently published peer reviewed scientific articles, and conference papers accepted had no significant effect. Scientific legitimacy measured as publications in non-peer review journals even had a negative effect. Popular legitimacy showed mixed results. Measured as number of articles in popular science publications showed positive correlations and other public media appearances had a non significant effect on start-up propensity. Individuals who are older and have higher level of human capital, measured as level of education are less likely to start firms. We also found that, people with more social capital, such as contact with external product development teams are more likely to start new firms. Taken together, the findings suggest that activities spanning the university-business divide increase the start-up propensity, while within university activities had no, or negative effects on the propensity. Consequently, universities interested in encouraging their employees to start firms should focus their attention on creating spanning activities rather than improving conditions for within university tenure.