When English Isn’t the Best Teacher: Source Language Effects in Cross-Lingual In-Context Learning
Fred Philippy, Siwen Guo, Jacques Klein, Tegawendé F. Bissyandé
Abstract
Cross-lingual transfer in multilingual NLP has been widely explored in supervised fine-tuning contexts, where factors like data availability and linguistic similarity largely determine transfer quality. As the field shifts toward few-shot In-Context Learning (ICL), it is often presumed that insights from fine-tuning carry over unchanged. Yet this assumption has not been rigorously evaluated, leaving open the question of how to choose source languages for cross-lingual ICL. We conduct a broad empirical study of cross-lingual transfer in ICL spanning seven tasks, six models, and a typologically diverse set of languages. We further analyze language confusion, a key obstacle for generative tasks in cross-lingual ICL. Our results show that conventional fine-tuning-based expectations do not consistently apply in the ICL regime and point to alternative heuristics for selecting source languages effectively..- Anthology ID:
- 2026.mellm-1.31
- Volume:
- Proceedings of the 1st Workshop on Multilinguality in the Era of Large Language Models (MeLLM 2026)
- Month:
- July
- Year:
- 2026
- Address:
- San Diego, United States
- Editors:
- Kaiyu Huang, Fengran Mo, Pinzhen Chen, Meng Jiang
- Venues:
- MeLLM | WS
- SIG:
- Publisher:
- Association for Computational Linguistics
- Note:
- Pages:
- 317–326
- Language:
- URL:
- https://preview.aclanthology.org/ingest-acl-workshops/2026.mellm-1.31/
- DOI:
- Cite (ACL):
- Fred Philippy, Siwen Guo, Jacques Klein, and Tegawendé F. Bissyandé. 2026. When English Isn’t the Best Teacher: Source Language Effects in Cross-Lingual In-Context Learning. In Proceedings of the 1st Workshop on Multilinguality in the Era of Large Language Models (MeLLM 2026), pages 317–326, San Diego, United States. Association for Computational Linguistics.
- Cite (Informal):
- When English Isn’t the Best Teacher: Source Language Effects in Cross-Lingual In-Context Learning (Philippy et al., MeLLM 2026)
- PDF:
- https://preview.aclanthology.org/ingest-acl-workshops/2026.mellm-1.31.pdf