Co-Distillation: Training Teacher and Student Together

~12 min read

Instead of a fixed, already-trained teacher, co-distillation starts with BOTH an untrained teacher and an untrained student, training them simultaneously — what Llama 4 used to train Scout and Maverick from Behemoth.

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Key points

  • Co-distillation starts with an UNTRAINED teacher AND an untrained student, training both simultaneously, not a fixed already-trained teacher
  • The teacher trains normally on ground-truth hard labels; the student trains to match the teacher's (evolving) soft probabilities
  • Bootstrapping problem: early in training, the teacher's soft labels aren't accurate yet
  • Fix: the student trains on BOTH the teacher's soft labels AND ground-truth hard labels simultaneously, not purely on the teacher's guidance
  • Llama 4 used co-distillation to train Scout and Maverick from Behemoth — a pre-training-stage technique, unlike hard-label distillation's post-training use