The Holarctic Scopula cajanderi (Herz) species group is revised on the basis of external and genitalic characters. The taxa included in the species group are Scopula cajanderi (Herz, 1903 [not 1904]) (= the Palaearctic Scopula elwesi sajanensis Prout, 1935 syn.nov., = the Palaearctic Scopula elwesi achlyoides Prout, 1935 syn.nov., = the Nearctic Scopula septentrionicola McDunnough, 1939 syn.nov.), thus making S. cajanderi Holarctic; Scopula mustangensis Yazaki, 1995; and Scopula aegrefasciatasp.nov. Lectotypes are designated for the following species which were described from more than one specimen without holotype designation: S. cajanderi, Scopula anaitaria (Herz, 1903), and S. e. achlyoides. The systematic position of Scopula elwesi elwesi Prout, 1922 within the genus Scopula is uncertain. A key to the species is presented with illustrations of the adults and genitalia, and a distribution map is presented for all taxa. An examination of the biogeography of S. cajanderi suggests that the Wisconsinan and Sartan glaciations may have played a part in the origin of the disjunct populations.