The focus of the thesis is on labour, business, social and cultural history of Italian immigration to post WWII Toronto. In particular, this study addresses fundamental issues such as ethnic niching, unionization, urban proletarianization and entrepreneurship. From this perspective, this investigation addresses and analyses a list of key questions. How did a mass of former peasants, unskilled workers, artisans and merchants become urban wage-earners or small business entrepreneurs in an urban and Capitalist society? How did the process of unionization work? How did an economic ethnic niche develop? What role did 'ethnicity' play in the processes of both urban proletarianization and unionization as well as entrepreneurship? What made immigrant unionization and entrepreneurship successful or a failure? What other factors impinged on these processes? Lastly, what impact did these processes have on the host society? In addressing these questions the thesis focuses on the role played by a specific industry in enabling immigrants to find their place in the new host society. More specifically, the research has looked at the construction industry that, between the 1950s and the 1970s, represented a typical economic ethnic niche for the Italian community. In fact, tens of thousands of Italian males found work in this sector as bricklayers, labourers, carpenters, plasterers and cement finishers, while hundreds of others became small employers in the same industry. The analysis of the cultural and structural factors that were at the origin of the Italian niche of the construction industry is the central point of this study.