Although academic entrepreneurship has been of growing public policy interest in recent years, the incubation of spin-off companies is still a neglected issue in the academic literature. This paper explores the initial entrepreneurial phase whereby university scientists convert a technological idea based on public-domain knowledge into a business project. The foundations of a conceptual framework are established, drawing upon the resource-based theory of the firm and entrepreneurship theories. Fundamental concepts such as opportunities and resources are reviewed and a basis of systematic comparison between enterprises is proposed through the analysis of two case-studies on early academic enterprise in the University of Cambridge, UK. Launching an academic spin-off is a collective endeavour involving the recognition of opportunities and the building of technological resources offering potential for value creation. The nature of the technology and market maturity are important factors in the explanation of the path followed by scientists-entrepreneurs incubating a company.