This study assesses both the social polarisation hypothesis and the role migrants play in this process, using survey and population census data of the Johannesburg region of South Africa from 1970 to 2010. The manufacturing sector, once a major source of urban employment and consisting of a large percentage of skilled and semi-skilled, middle-income jobs has declined while the service sector, argued to consist of predominantly either high-skill, high-pay or low-skill, low-pay jobs, has grown. Thus, the decline of manufacturing and the growth of the service sector are argued to result in a more polarised society. Low-wage, low-skill service sector jobs are also argued to attract poorly-educated, unskilled immigrants unable to compete in the urban labour market for anything other than low-skill, low-pay jobs. Thus, the contention is that immigration contributes to social polarisation.