This study investigates the effects of the following factors on established business owners’ success. First, the human capital of the entrepreneur is examined (education, experience, locus of internal control, need for achievement and resilience). Second, the characteristics of the firm with reference to the initial financial resources, number of partners, frequency and breadth of external communication are taken into consideration, and finally, factors relevant to the conception and development of the firm are studied. To achieve our objective, we have used a structural equation modeling technique (Partial Least Squares -PLS-) to estimate a path model with latent variables. Although all the latent variables have a positive impact on established business owners’ success, our findings show clearly that the size of the company is an important moderating factor when explaining established business owners’ success. The variables in which this effect is most evident are that of education and resilience. If we do not take the size of the company into consideration, the variables that help explain the success of established business owners are, in order of decreasing importance, experience, a favorable perception of the business environment and the resilience of the entrepreneur.