This is a draft version of a book that aims to provide an in-depth description and analysis of the tone system of Yongning Na, a Sino-Tibetan language spoken in Southwest China. The draft has been circulated among colleagues since 2012. A first version was deposited in the HAL-SHS archive in 2014 under the title "The tonal grammar of Yongning Na"; the title was later changed to "Tone in Yongning Na: lexical tones and morphotonology". The draft is currently (2016) being circulated before submission to Language Science Press. Readers are most welcome to send me comments (alexis.michaud@vjf.cnrs.fr)