These proceedings contain the contributed papers from the first International Workshop on Implicit Author Characterization from Texts for Search and Retrieval (IACT'231) held in conjunction with the 46th International ACM SIGIR Conference on Research and Development in Information Retrieval in Taipei, Taiwan, on the 27th of July 2023. Six papers were submitted for peer review to this workshop. Out of them, four research papers were accepted for publication. Each submitted paper was reviewed by three members of an international program committee. In addition to the selected papers, the workshop featured two invited speakers: Prof. Mark Last and Prof. Dr. Valia Kordoni. Mark Last gave a talk entitled “20 Years of Analyzing Multilingual Propaganda Content on the Web”. Valia Kordoni gave a talk entitled ”The Promises and Perils of AI Information Retrieval”. This volume also contains a report on the competition on Automatic Classification of Literary Epochs (CoLiE), which was held as part of the workshop. We would like to thank SIGIR for hosting us, our keynote speakers, the program committee, the paper authors, and the participants who have made this workshop possible. Editor Alípio Jorge was financed by National Funds through the FCT-Fundação para a Ciência e a Tecnologia, I.P. (Portuguese Foundation for Science and Technology) within the project StorySense, with reference 2022.09312.PTDC. Editor Ricardo Campos was financed by the ERDF European Regional Development Fund through the North Portugal Regional Operational Programme (NORTE 2020), under the PORTUGAL 2020 and by National Funds through the Portuguese funding agency, FCT - Fundação para a Ciência e a Tecnologia within project PTDC/CCI-COM/31857/2017 (NORTE-01-0145-FEDER-03185). Editors Marina Litvak and Irina Rabaev were supported by the Internal SCE grant - Excellence Research Track B, no. EX/06-BY22/T1/D3/Yr1.
Editors Web and Dissemination Chair Shay Shabtay, Shamoon College of Engineering Hugo Sousa, INESC TEC & University of Porto