Kungliga Vitterhets Historie och Antikvitets Akademien
Ahnlund was a popularizer of history and became widely known for his contributions in newspapers and radio, but in academia he was also successful and became, among other things, a member of the Royal Swedish Academy of Letters, History and Antiquities as early as 1934 and the Swedish Academy. He was also made a member of several Nordic academic societies as well as vice president of the Comité International des Sciences Historiques.