Nathan Lambert

Nathan Lambert

AI Researcher & Author, Interconnects

About

Nathan Lambert is a machine learning researcher known for his work on post-training and reinforcement learning from human feedback (RLHF). He earned his PhD at UC Berkeley working on model-based reinforcement learning for robotics, helped build the RLHF research team at Hugging Face, and later led post-training at the Allen Institute for AI (Ai2), where he shaped fully open model families like OLMo and Tülu. He is the author of the reference textbook on RLHF and writes Interconnects, a widely read technical newsletter on AI models and research. In 2026 he departed Ai2 to found a new AI lab, and remains one of the most visible advocates for open-source AI development in the United States.

Key Contributions

  • Led post-training at the Allen Institute for AI (Ai2), shaping fully open model families like OLMo and Tülu with open weights, data, and training code
  • Wrote the reference textbook on reinforcement learning from human feedback (RLHF), distilling the technique behind modern chat models
  • Helped build the RLHF research team at Hugging Face, contributing to open tooling like TRL and early open aligned models like Zephyr
  • Writes Interconnects, a technical newsletter on AI models and research that draws millions of views annually
  • A leading advocate for open-source AI in the US; his 2026 visit to Chinese AI labs offered a rare firsthand American account of China's open-model ecosystem

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