This article investigates the influence of informal and formal institutions on the university students' decision of becoming employer entrepreneurs (university students that create a new firm with employees) in the context of Catalonia. A sample of 1207 students from the Universitat Autònoma de Barcelona (UAB) and the Universitat Oberta de Catalunya were surveyed for the period of 2012-2015, and Probit regressions over pooled data were used. The main findings suggest that formal factors (university's lack of incentives to create a new business, entrepreneurial knowledge, training and skills, and entrepreneurship education) are higher correlated with the student employer entrepreneurs than informal institutions (role models, entrepreneur's social image and fear of failure). Despite that the entrepreneur's social image does not seem to have an influence on the entrepreneurial decision of university students, the other variables analysed are statistically significant, correlated with entrepreneurship as a choice. Specifically, entrepreneurship education is the most relevant variable in explaining the decision of university students becoming employer entrepreneurs. The paper contributes with policy discussions in order to extend the current debate about the role of the universities in the entrepreneurial process and also the importance of entrepreneurial universities to the society.