Based on the eclectic theory, the paper analyzes which are the basic factors leading to the creation of new start-ups in society. It is argued that an ecosystem prone to entrepreneurship must own opportunities created by market conditions, human capital and resources such as access to capital or R & D and technology. Stability and economic growth act positively on the expectations of people who are in the situation of deciding whether or not to create the company they are projecting. But at the same time, macroeconomic conditions such as the behavior of demand or the degree of economic stability affect the context in which entrepreneurs identify opportunities and decide if they are going to undertake. Given this reverse causality, econometric estimations are carried out using panel data techniques, instrumental variables and simultaneous three-phase equations. Regional data are used in Spain over the period 2008-2014. The results also show that entrepreneurship of the small companies, as well as those of low technology sectors, is directly related to the availability of credit. And the entrepreneurship rate of large companies or high technological intensity is explained by the resources available to companies such as the availability of R & D capital or human capital as well as industrial diversity or demographic composition. Implications from the findings are discussed.