Aydoğan, ReyhanBaarslag, T.Fujita, K.Mell, J.Gratch, J.de Jonge, D.Mohammad, Y.Nakadai, S.Morinaga, S.Osawa, H.Aranha, C.Jonker, C. M.Bassiliades, N.Chalkiadakis, G.de Jonge, D.2021-10-122021-10-122020978-303066411-40302-9743http://hdl.handle.net/10679/7634https://doi.org/10.1007/978-3-030-66412-1_23The Automated Negotiating Agents Competition (ANAC) is a yearly-organized international contest in which participants from all over the world develop intelligent negotiating agents for a variety of negotiation problems. To facilitate the research on agent-based negotiation, the organizers introduce new research challenges every year. ANAC 2019 posed five negotiation challenges: automated negotiation with partial preferences, repeated human-agent negotiation, negotiation in supply-chain management, negotiating in the strategic game of Diplomacy, and in the Werewolf game. This paper introduces the challenges and discusses the main findings and lessons learnt per league.engrestrictedAccessconferenceObject1252036638100106143640002310.1007/978-3-030-66412-1_232-s2.0-85101310681