The article deals with “racial” aspects of the labour market and labour relations in South Africa's building industry, focussing largely, though not exclusively, on skilled building workers on the Witwatersrand (Southern Transvaal). Different trade-union strategies are examined, as pursued by building trade unions in the Transvaal as well as the Eastern Cape and Natal, in order to add a comparative dimension. In the latter areas, shortly after World War I, a white-exclusionist organizing policy was replaced in some urban centres by a pragmatic strategy of incorporating “coloured” artisans (Africans and Indians continued to be excluded). In the Transvaal, on the other hand, the relatively strong position of white building workers and a deeply-ingrained racism ensured the maintenance of racially-exclusive trade unionism in the building industry.