ENThis article investigates the misconception that Herder was allegedly unable to differentiate between Lithuanians and Latvians, or between the Latvian and Lithuanian language and folksongs. In his Ueber die neuere Deutsche Litteratur Herder indicated two Lithuanian songs that he identified as Latvian, an apparent misunderstanding that was ascribed to Herder’s ignorance, confusion, etc. By analysing the 18th century history of the term lettisch this article argues that this is not the case. Herder’s usage of the term follows a little-known 18th century academic habit of putting both Lithuanians and Latvians under the terminological umbrella of Lettorum/Letten. A more precise reading of Herderian texts reveals that his allegedly obscure terminology is indeed clear and consistent.