The Newman–Kwart rearrangement is a type of rearrangement reaction in which the aryl group of an O-aryl thiocarbamate, ArOC(=S)NMe₂, migrates from the oxygen atom to the sulfur atom, forming an S-aryl thiocarbamate, ArSC(=O)NMe₂. The reaction is named after its discoverers, Melvin Spencer Newman and Harold Kwart.