Group size is normally small. Tamarins have been found in association with cebids, marmosets, and other tamarins. Some will respond to the alarm calls of other tamarins. There is still much to be learned, with field studies lacking for a couple of species. Most seem to have a breeding and birth season.
Twins are the norm, though single births and triplets are sometimes seen.
Infants are raised communally, with all adults food sharing with the young. Fathers carry the infants quite a bit, sometimes more than the mothers. Participation in the rearing of younger siblings can prepare young females to care for their own offspring. There is still a lot to be learned about tamarin reproductive patterns. The average life span for tamarins seems to be early to mid-teens, although some species can live 20 years, and a couple don't make it into the teens.