This tree-dwelling primate is solely active during the daylight hours, particularly in the cooler mornings and late afternoons (2). It lives in stable troops of 2 to 15 individuals, usually consisting of an adult pair and their offspring (2). They rest huddled together at night, often in a dense tangle of vines (4), around seven to ten metres above the ground (2).
Moving around its forest habitat by running along branches, up and down trunks, and leaping between trees, the pygmy marmoset feeds on fruits, buds, insects, and exudates from trees (2). Its lower canine teeth are specially suited to gouging holes in trees to enable it to feed on exudates, and within the range of each marmoset group one or more trees can be found which are riddled with holes (2).
The majority of pygmy marmoset births occur in two peaks each year: between November and January, and May and June (2). In captivity, gestation lasts around 20 weeks and most of the births are of twins (2) (5). Sexual maturity is reached between 18 and 24 months and one pygmy marmoset is known to have lived for over 11 years (2).