The paper develops a conceptual framework to analyze the causes and mechanisms of business group formation by habitual entrepreneurs. Data for analysis are drawn from a database regarding a sample of groups of Italian manufacturing businesses. The empirical analysis shows that business group formation by habitual entrepreneurs is mainly the result of a growth process around the original business. Several levels of entrepreneurship can be distinguished in this process. Firstly the emergence of new ventures to exploit the specialized market niches or regionally segmented markets that are typical of the small business sector. Secondly the creative extraction of value from manipulating legal forms.