Multimodal Large Language Models for Low-Resource Languages: A Case Study for Basque
Proceedings of the Fifteenth Language Resources and Evaluation Conference (LREC 2026)
Abstract
Current Multimodal Large Language Models exhibit very strong performance for several demanding tasks. While commercial MLLMs deliver acceptable performance in low-resource languages, comparable results remain unattained within the open science community. In this paper, we aim to develop a strong MLLM for a low-resource language, namely Basque. For that purpose, we develop our own training and evaluation image-text datasets, leveraging state-of-the-art translation systems. Using two different Large Language Models as backbones, the Llama-3.1-Instruct model and a Basque-adapted variant called Latxa, we explore several data mixtures for training, encompassing Basque and English languages for both multimodal and text-only data. Evaluating our MLLMs for close-ended and open-ended generation tasks, we show that: i) low ratios of Basque multimodal data (around 20%) are already enough to obtain solid results on Basque benchmarks, and ii) contrary to expected, a Basque instructed backbone LLM is not required to obtain a strong MLLM in Basque. Additionally, we specify the optimal data mixture strategy, the effects of multimodal data in text-only tasks, and analyze evaluation approaches for open-ended generation tasks. Our results pave the way to develop MLLMs for other low-resource languages by openly releasing our resources.