ResearchResearch paperLarge Language Models · Safety & Alignment1 source · Oct 19, 2026

Safety Mid-Training: Internalizing LLM Safety as a Foundational Capability

We introduce safety mid-training, a stage between pre-training and post-training that jointly develops safety and general reasoning through this shared structure.

Key points

  • Safety alignment for large language models (LLMs) is primarily performed during post-training, while recent work has also begun incorporating safety data into pre-training.
  • We instead view safety as an LLM capability that can be learned through a reasoning structure shared with general tasks.
  • Given safety and utility prompts, the base model generates structured documents and reasoning traces that are then used for mid-training.
  • Together, these results suggest that learning safety and general reasoning within a shared mid-training stage can reduce the safety-utility trade-off and make safety more robust to subsequent training.

Sources (1)

  • [1]Safety Mid-Training: Internalizing LLM Safety as a Foundational Capability
    arXiv (AI, ML, NLP, CV, robotics, multi-agent) · Oct 19, 05:49 PM
    We introduce safety mid-training, a stage between pre-training and post-training that jointly develops safety and general reasoning through this shared structure.
    Safety alignment for large language models (LLMs) is primarily performed during post-training, while recent work has also begun incorporating safety data into pre-training.

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