This Special Topic describes the current state and new developments in neutron diffraction. However, the innovations are continuing, with concepts being explored to complete the instrument suites at the first target station at the SNS, upgrade diffraction suite capabilities at the HFIR, and indeed the design and instrumentation for a future second target station at the SNS. We are confident these new developments will help us meet the challenges for neutron diffraction in the coming decades. Capabilities at the HFIR and SNS broadly support scientific exploration in biology, chemistry, physics, materials science, geoscience, medicine, and more. The Special Topic connects technical advancements with the scientific discoveries they enable, providing a platform for increased visibility and stimulating further developments. The topic is divided in four parts: (1) Diffraction Suite Reviews; (2) State-of-the Art Neutron Instruments ; (3) Novel Neutron Sample Environments; and (4) Advances in Neutron Diffraction Measurements.
