All species are arboreal forest dwellers. They are active, quadrupedal animals that run and walk on horizontal and diagonal branches and are capable of leaping to and from vertical and horizontal supports. Resting postures range from sitting upright to lying sprawled on a horizontal branch. Most activity is diurnal. Social organization in Eulemur is variable.
Lemurs appear to be territorial.
There usually is a single young, though twins are not rare. Lemurs thrive in captivity and are often exhibited in zoos. The relatively high population densities reported in field studies may be misleading in that they generally apply only to small, protected reserves. The IUCN classifies E. macaco flavifrons as endangered, E. macaco macaco and E. mongoz as vulnerable, and E. rubriventer as indeterminate. In addition to habitat destruction, these forms reportedly are threatened by intensive hunting and trapping because of their alleged raids on crops.