Massively Multilingual Adaptation of Large Language Models Using
  Bilingual Translation Data
Authors: name: Shaoxiong Ji; name: Zihao Li; name: Jaakko Paavola; name: Indraneil Paul; name: Hengyu Luo; name: Jörg Tiedemann
Published: 2025-05-31 08:37:17

Abstract: This paper investigates a critical design decision in the practice of
massively multilingual continual pre-training -- the inclusion of parallel
data. Specifically, we study the impact of bilingual translation data for
massively multilingual language adaptation of the Llama3 family of models to
500 languages. To this end, we construct the MaLA bilingual translation corpus,
containing data from more than 2,500 language pairs. Subsequently, we develop
the EMMA-500 Llama 3 suite of four massively multilingual models -- continually
pre-trained from the Llama 3 family of base models extensively on diverse data
mixes up to 671B tokens -- and explore the effect of continual pre-training
with or without bilingual translation data. Comprehensive evaluation across 7
tasks and 12 benchmarks demonstrates that bilingual data tends to enhance
language transfer and performance, particularly for low-resource languages. We
open-source the MaLA corpus, EMMA-500 Llama 3 suite artefacts, code, and model
generations.