The Brown Lemur's mating season is May and June. After a gestation of 120 days, the young are born. Single births are most common, but twins have been reported. The young are weaned after about 4 to 5 months. Sexual maturity occurs at about 18 months Life span in captivity can be as long as 30 years.

The Common Brown Lemur lives in western Madagascar north of the Betsiboka River, as well as in inland Madagascar connecting the eastern and western ranges. They also live on the island of Mayotte, although this population is believed to have been introduced there by man in the early 1900’s

They normally live in groups of 5 to 12, but group size can be larger, especially on Mayotte. Groups include members of both sexes, including juveniles, and there are no discernible dominance hierarchies. Unlike most other lemurs.
They are primarily active during the day, but activity can continue into the night, especially during full moons and during the dry season.