William Labov ( ; born December 4, 1927) is an American linguist, widely regarded as the founder of the discipline of variationist sociolinguistics. He has been described as "an enormously original and influential figure who has created much of the methodology" of sociolinguistics. He is employed as a professor in the linguistics department of the University of Pennsylvania, and pursues research in sociolinguistics, language change, and dialectology. He semi-retired at the end of spring 2014.