Divide-and-Adapt: Fine-Tuning VLMs via Model Division and Routing

Hailing Wang, Neil Rodrigues, Xianglong Wang, Wei Li, Lin Chen, Yun Fu


Abstract
Fine-tuning Vision-Language Models (VLMs) is a common practice to adapt pre-trained models for downstream tasks. Yet existing fine-tuning methods consistently keep the pre-trained architecture intact, leaving open the question of whether maintaining such structural integrity is truly necessary for effective adaptation. To investigate this, we propose Divide-and-Adapt, a new fine-tuning paradigm that departs from preserving the full pre-trained structure. It first divides the pre-trained model into multiple downstream-oriented subnetworks, and then adapts them collaboratively through a routing-based coordination mechanism. This design facilitates the selection of structures that are most beneficial for downstream tasks and enables their collaborative integration. Remarkably, even without any task-specific training, our Divide-and-Adapt framework first divides the pre-trained model into downstream-oriented subnetworks and adaptively activates them for downstream inference, already outperforming the pre-trained model on downstream tasks. With further fine-tuning, Divide-and-Adapt surpasses both full fine-tuning and parameter-efficient baselines across multiple benchmarks, demonstrating its effectiveness. Our code will be made publicly available at https://github.com/haiiling/DivideAndAdapt.
Anthology ID:
2026.emnlp-main.615
Volume:
Proceedings of the 2026 Conference on Empirical Methods in Natural Language Processing
Month:
October
Year:
2026
Address:
Budapest, Hungary
Editors:
Hung-Yi Lee, Sunipa Dev, Jessy Li, Desmond Elliott
Venue:
EMNLP
SIG:
SIGDAT
Publisher:
Association for Computational Linguistics
Note:
Pages:
14137–14151
Language:
URL:
https://aclanthology.org/2026.emnlp-main.615/
DOI:
Bibkey:
Cite (ACL):
Hailing Wang, Neil Rodrigues, Xianglong Wang, Wei Li, Lin Chen, and Yun Fu. 2026. Divide-and-Adapt: Fine-Tuning VLMs via Model Division and Routing. In Proceedings of the 2026 Conference on Empirical Methods in Natural Language Processing, pages 14137–14151, Budapest, Hungary. Association for Computational Linguistics.
Cite (Informal):
Divide-and-Adapt: Fine-Tuning VLMs via Model Division and Routing (Wang et al., EMNLP 2026)
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PDF:
https://aclanthology.org/2026.emnlp-main.615.pdf