Grey-capped social weavers breed colonially. The nests are not only used for breeding but also for fully grown birds to sleep in at night. Breeding takes place throughout the year, but there is a peak that enables the birds to make use of periods that food is plenty, such as between August and December in South Sudan and between March and May in eastern Africa. Nests are built hanging from thin branches, often in "Vachellia drepanolobium", and sometimes in other acacia species such as the umbrella thorn acacia ("V. tortilis"), blackthorn ("Senegalia mellifera") or gum acacia ("S. senegal"). The roofed nests have thick walls and are constructed from grass straws, which, in the dry climate keep well for many months. Nest are often constructed with two or three side-to-side or under old nests. One of the two entrances is closed just before the eggs are laid and opened again around the moment of fledging. The clutch consists of four eggs. They are approximately in length and in diameter, greenish, bluish or white, unadorned or with fine black or olive colored specks, more dense at thick end, or so heavily blotched that the overall color seems olive-brown or ash-grey. Both parents incubate the eggs but the female spends about twice as much time incubating as the male. The eggs hatch after thirteen or fourteen days. The nestlings are initially fed on a diet consisting exclusively of insects, and grass seeds are only given during the last days. Fledging occurs after about twenty days. Adult and adolescent birds from previous broods often help in nest building and feeding the chicks.