At the beginning of 2022, the Latvian Academy of Sciences received a notification from the Latvian National Commission for UNESCO that the 150th anniversary of the linguist Jānis Endzelīns was included in the UNESCO 2023 calendar of commemorations and anniversaries. The article dwells on Jānis Endzelīns’ contribution to Indo-European, Baltic, and Latvian linguistics, Latvian education and culture.