How to build a diffusion language model

An introduction to diffusion language models and the research advances that underlie today's diffusion LLMs. We describe the building blocks of recent open-source models, starting from simple masking diffusion, and including techniques for iterative refinement, post-training, and variable-length generation. Material is adapted from workshop talks and lectures at ICLR 2026 and MLSS 2026. Two famili...