Abstract This article investigates the impact of social network size on business performance based on GEM (Global Entrepreneurship Monitor) data of Iran, Croatia and Denmark in 2008-2010. A sample of 1801 owner-managers participated in the GEM interviews is used. Social network of an entrepreneur is made up of private, job, experience, professional and market networks. Exploratory factor analysis shows that the experience network and private network have the highest and lowest factor loadings respectively (0.9 and 0.37). Similarly, in factor analysis of performance as a latent variable the highest factor loading is for export (0.33) and the lowest is for growth expectation (0.05). The results show that Danish entrepreneurs establish their business mostly to exploit opportunities (75%) rather than having no better job option. Most of them also have role models (more than 70%). In these regards Denmark has higher rank than Iran and Croatia. On average the entrepreneurs’ social network size in Iran is 2.9 while in two other countries, it is 6. The size of private network is higher than size of other networks in Iran (1.61). The result of structural equation modelling shows that business performance (innovation, export and growth expectation) is affected significantly by social network size (74%) and this effect is moderated by role model (0.07%) and opportunity motivation (7.2%). Keywords: Social Networks, Business Performance, Opportunity Motivation, Role Model.