The Cinnamon-faced Tyrannulet is one of the least-known species of the Andes. Although it first was collected in southern Peru in 1899, it was confused with a similar species found in Venezuela, the Rufous-lored Tyrannulet (Phylloscartes flaviventris). The Cinnamon-faced Tyrannulet was not observed again by ornithologists until 1972, and not until the early 1980s was it sufficiently well-known to be recognized as a distinct species. Its distribution is confined to the canopy of humid montane forest in a narrow elevational zone on the lower slopes of the east side of the Andes, from central Peru to northern Bolivia. The English name refers to a narrow band of cinnamon-rufous near the eyes and on the lores and forecrown. Although distinctive, this cinnamon "face" can be difficult to discern in the field. The Cinnamon-faced Tyrannulet is more readily identified by its horizontal posture, active behavior, olive-yellow underparts, yellow wingbars, and buff and black auriculars. The specific epithet, parkeri, is a tribute to the late Theodore A. Parker III, in recognition of his "skill in the field [and] unbridled enthusiasm for birds and conservation."