This paper investigates fertility among African women in South Africa. Variation in fertility levels is influenced by such factors as rural or urban residence, and level of education and household income. Differential fertility between women of different language groups is accounted for largely by underlying socio-economic factors. A further factor investigated by this paper is the impact of household structure on fertility in South Africa using the 1993 South Africa Living Standards and Development Study. Household structure is examined from the perspective of women. We focus on whether women live with a husband, or with relatives of their parents' generation, or with relatives of their own generation. The analysis concentrates on women aged twenty or over who are already mothers. For these women, we hypothesise that living arrangements mediate between their socio-economic and cultural characteristics and the number of children that they have borne. Living with relatives from the previous generation is found to have a negligible net impact on the lifetime fertility of mothers. However, women who live with relatives from their own generation have borne about a fifth fewer children than other women of the same age after controlling for the impact of household income, the woman's schooling, regional differentials and urban‐rural residence. Women from Nguni language groups have relatively large families. While this largely reflects economic and educational disadvantage, it is also conditional on their living arrangements. Unmarried and separated mothers have about a fifth fewer children than married mothers of the same age. It is within the domestic context that the influence of other characteristics is transmuted into differences in numbers of children. Women's living arrangements have become more diverse over the past thirty years in South Africa. They both modify and mediate the effects of other factors on fertility.