A number of runic inscriptions from the entire Germanic area from between A.D. 200 and 800 exhibit non-etymological, epenthetic vowels, such as worahto for *worhto ‘did’. An analysis of all (likely) instances of epen­thesis in early Ger­manic languages shows that epenthesis developed only in clusters involv­ing /r/, /l/ or /n/.Epenthesis was an optional feature of nearly every early Germanic dialect, being most abundantly attested in southern Sweden. There is no statis­ti­cally sig­nif­icant evidence of an increase or decrease in the amount of epenthesis dur­ing the period. A detailed analysis reveals two different phonological en­vi­ron­ments for epenthesis. Scandinavian attestations of epenthesis oc­cur most­ly in heterorganic consonant clusters, irrespective of their sonority se­quence, where epenthesis is a result of a transition in articulatory gestures. The epenthetic vowels appear as a (or ᴀ) in Scandinavia. In inscriptions from south­ern Germany, however, epenthetic vowels are concentrated in clusters with a marked sonority sequence, irrespective of their place of artic­u­la­tion. While the epen­thetic vowels in the inscriptions from Germany are either a or u, the few po­tential instances of epenthesis in marked sonority se­quences in Scan­di­navia are rendered by vowels other than a. The epenthetic vowels in Anglo-Frisian in­scrip­tions resemble the Scandinavian type, but only partially.