Neurophotonics is publishing a Special Section on fNIRS. This special section brings together papers presented at the fNIRS conference held in October 2016 in Paris, as well as other contributed papers on near-infrared spectroscopy. The conference had sessions covering the development and use of NIRS. These spanned the topics of neurodevelopment, brain and systemic physiology, clinical applications, multimodal monitoring, hardware development, global fNIRS, neonatal and pediatric applications, data analysis, and neurocognition. The Special Section has received such a high number of submissions that it is being published in three parts. Part 1 appeared in Vol. 4, Issue 2 and consisted of six papers. Part 2 and Part 3 are currently in progress, with Part 2 appearing in Vol. 4, Issue 4, and Part 3 appearing in Vol. 5, Issue 1. Currently, twelve papers have been published in Part 2 and thirteen papers have been published in Part 3, with more to come. The tables of contents for all three issues can be accessed at neurophotonics.spiedigitallibrary.org