On October 14, 2021, one hundred years had passed since the establishment of diplomatic relations between Lithuania and Finland. A history conference was held on October 12, 2021, in Helsinki to celebrate the centenary. The organizers were the Faculty of Humanities of the University of Oulu, the Faculty of History of the University of Vilnius, Donelaitis-seura, the Lithuanian Embassy to Finland, and the Finnish Embassy to Lithuania. This compilation brings together the presentations given at the history conference that have been expanded and updated into scientific articles. In addition to them, two invited articles complete the whole.