The offspring become sexually mature at 12 to 18 months. They reach adult size by the age of two. This marmoset is diurnal and arboreal. They are active and agile creatures, running, jumping, and occasionally leaping among trees and shrubs. They move through the trees by running quadrupedally along horizontal branches and leaping between thin terminal supports.
Pygmy marmosets are usually docile and gentle.
Mutual grooming is often seen between members of groups. Pygmy marmosets mark and defend territories from 25 to 100 acres. They mark their territory with scent glands located on the chest and suprapubic area. Defense of their territory involves calls, displays, and sometimes chasing away others. Habitat Pygmy marmosets occupy trees and shrubs in tropical and floodplain forests.