Sequential Beats Joint: On the Interplay between On-Policy Distillation and RLVR

Boyan Li, Bingsen Chen, Chenghao Yang, Ping Nie, Chen Zhao, Xi Ye


Abstract
Reinforcement learning with verifiable rewards (RLVR) and on-policy distillation (OPD) have emerged as two dominant methods for post-training reasoning LLMs. Prior work uses OPD’s dense token-level supervision to complement the sparse RL reward, fusing the two signals within a single step: either as a weighted-additive combination or a teacher-modulated rescaling of the RL advantage. In this paper, we show that a simple two-stage scheme, OPD-then-RL, consistently outperforms pure OPD, pure RLVR, and all such joint baselines across logic and math reasoning benchmarks. Beyond the empirical results, we further provide a systematic understanding of this through pass@k behavior, learning dynamics, and parameter updates, yielding a consistent explanation: OPD expands the student’s coverage of teacher-supported solutions and RL sharpens within that support, while jointly optimizing the two signals causes them to interfere. To provide a practical recipe, we find that the OPD validation score is the key signal for when to switch to RL, and that OPD is a better cold start for RL than SFT. Together, our results establish OPD-then-RL as a simple yet strong way to combine the two methods, turning two entangled signals into complementary stages.
Anthology ID:
2026.findings-emnlp.631
Volume:
Findings of the Association for Computational Linguistics: EMNLP 2026
Month:
October
Year:
2026
Address:
Budapest, Hungary
Editors:
Hung-Yi Lee, Sunipa Dev, Jessy Li, Desmond Elliott
Venue:
Findings
SIG:
SIGDAT
Publisher:
Association for Computational Linguistics
Note:
Pages:
13252–13270
Language:
URL:
https://aclanthology.org/2026.findings-emnlp.631/
DOI:
Bibkey:
Cite (ACL):
Boyan Li, Bingsen Chen, Chenghao Yang, Ping Nie, Chen Zhao, and Xi Ye. 2026. Sequential Beats Joint: On the Interplay between On-Policy Distillation and RLVR. In Findings of the Association for Computational Linguistics: EMNLP 2026, pages 13252–13270, Budapest, Hungary. Association for Computational Linguistics.
Cite (Informal):
Sequential Beats Joint: On the Interplay between On-Policy Distillation and RLVR (Li et al., Findings 2026)
Copy Citation:
PDF:
https://aclanthology.org/2026.findings-emnlp.631.pdf