The Plain Antvireo is widely distributed across the neotropics where it is found from southeastern Mexico south to Bolivia in the western portion of its range, and from northeast Brazil to Paraguay in the eastern portion of its range. Males of the nominate race have a dark gray crown, grayish-olive upperparts with a white breast and a yellow center of the belly. Females have a chestnut crown and more olive upperparts. The eighteen recognized subspecies of Plain Antvireo all differ slightly in their coloration, with most subspecies appearing grayer in the males and browner in the females than the nominate race.
The northern and Andian populations of the Plain Antvireo usually occupy the understory and mid-story levels of humid, lower and montane evergreen forest. Populations in the eastern and southern portions of their range prefer moist terra firma and várzea forest . Plain Antvireos can be found in pairs or as members of mixed species flocks foraging near the ground 4 to 5 meters up. These birds are primarily perch gleaners, but they also make short sallies to glean items from nearby foliage or hover to snag prey from the underside of leaves. Both male and female Plain Antvireos take part in incubating their eggs. It has been observed that females generally incubate the eggs during the night, and that males generally incubate the eggs during the day.