The common brown lemur occupies a variety of forest types, including lowland rainforests, montane rainforests, moist evergreen forests and dry deciduous forests. They spend about 95% of their time in upper layers of the forest and less than 2% of their time on the ground. They normally live in groups of 5 to 12, but group size can be larger. Groups include members of both sexes, including juveniles, and there are no discernible dominance hierarchies. They are primarily active during the day. The common brown lemur's diet consists primarily of fruits, young leaves, and flowers.