A second language (L2), in its broad sense, refers to any language a person uses or studies besides the first language (L1). English is the most important L2 in Taiwan’s formal education, and Mandarin is the dominant L2 for foreign students. Japanese, Korean, Spanish, French, and German are also common L2s offered in university education, with Vietnamese, Indonesian, and Thai likewise becoming popular in general. An international conference specifically on L2 research and teaching not only facilitates the constructive interaction among teachers and researchers of various L2s but can also create virtuous synergy for all stakeholders. To enhance the quality and academic contribution of the event, this conference is held biennially. It takes place in odd-numbered years, followed by the publication of a selected proceedings volume in even-numbered years through an open-access model. The first conference was held in 2023, with the proceedings volume Current Issues in L2 Teaching and Research published in 2024. The second conference is scheduled for December 2025, with a proceedings volume of selected papers to be published in 2026. We warmly invite educators and researchers to submit papers and join us in advancing innovation and development in the field of second language teaching and research.