Mosquito net ownership is rising in sub-Saharan Africa but will substantially reduce malaria only if nets are used and the most vulnerable household members sleep under them. We used data from 9 large-scale household surveys conducted in 6 African countries from 2000 to 2004 that enumerated all household members and nets owned, analyzing only net-owning households. Across countries, women of reproductive age and children under 5 (without gender bias) were most likely to use the net; least likely were children of age 5-14 and adult males. Nets commonly covered 2-3 people. If a baby net was used, fewer people used the family net. Pregnant women were more likely to use a net in 2004 than in 2000. In several countries, a sizable minority of nets owned were not used. Understanding intra-household net-use patterns helps malaria control programs more effectively direct their efforts to increase their public health impact.