Most of the studies measuring and analysing technology transfer and knowledge spill-overs from universities turn to the databases collected by the universities which report the activities of the Offices of Technology Transfer. This book examines university scientist entrepreneurship not by asking the University Technology Transfer Offices what they do in terms of entrepreneurial activities, but rather university scientists directly what they do in terms of entrepreneurial activities. The results from this study are as startling and novel as they are revealing. While the Offices of Technology Transfer databases suggest that new firm start-ups by university scientists are not particularly a frequent occurrence, this book instead finds exactly the opposite. Most striking is that using a large database of scientists funded by grants from the United States National Science Foundation, this study finds that around 13 percent of scientists have started a new firm. These findings would suggest that university scientist entrepreneurship is considerably more prevalent that would be indicated by the data collected by the Offices of Technology Transfer and compiled by the Association of University Technology Managers (AUTM). In addition, the propensity for a university scientist to be engaged in entrepreneurial activity apparently varies considerably across scientific fields. In certain fields, such as computer and network systems, the prevalence of entrepreneurship is remarkably high, 23.8 percent. Similarly, in civil, mechanical, and manufacturing innovation, over one in five of the university scientists report starting a new business. The results from this study would suggest that the spill-over of knowledge from universities for commercialisation, innovation and ultimately economic growth, employment creation and global competitiveness is substantially more robust than had been previously thought.