The Streak-capped Antwren occurs in the lowlands of the Atlantic Forest region, in southeastern Brazil and adjacent portions of eastern Paraguay and northeastern Argentina. The crown is streaked black and white not only in the Streak-capped Antwren (in both sexes), but also in the closely related Orange-bellied Antwren (Terenura sicki) of northeastern Brazil. Both sexes of the Streak-capped Antwren also have a reddish brown back, and pale yellow underparts. Streak-capped Antwrens are very active when foraging, and primarily are found in the midstory and canopy of evergreen forest. These antwrens usually are encountered in pairs, and often accompany mixed species flocks of other insectivorous species. Although the Atlantic Forest region has experienced extensive habitat loss, the Streak-capped Antwren remains fairly common and is not considered to be a threatened species.