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.

拉波夫（W. Labov, 1927- ）美国语言学家，社会语言学的代表人物之一，宾夕法尼亚大学语言学教授。1927年12月4日出生于美国Rutherford。1948年在哈佛大学获得学士学位，1963年在哥仑比亚大学获得硕士学位，次年获得博士学位。1964年到1970年担任哥仑比亚大学助理教授，1971年至宾夕法尼亚大学任副教授，1976年担任该大学语言学实验室主任。1979年任美国语言学会主席，1986年还出任纽约语言学研究所萨丕尔教授席位。拉波夫早期师从魏茵莱希，重点研究语言与社会的关系，曾共同撰写一篇很有影响的论文《语言演变理论的经验基础》，为社会语言学、历史语言学的研究开拓了一个新方向。拉波夫主张把语言放到社会中去研究，反对索绪尔以语言、言语的区分为基础的"就语言而研究语言"的理论。这就使索绪尔以来的语言研究方向发生了重大的变化，使语言研究不再局限于语言系统内部，而是联系不同的社会因素具体考察它们如何影响语言的运转和演变，研究语言的变异，建立起一套富有特点的社会语言学的理论和方法。一大批社会语言学家形成了一个以拉波夫为学派领袖的"变异学派"。

William Labov.

Volume 1: Principles of Linguistic Change: Internal Factors,1994;

   the study of apparent time and real time; principles governing chain shifts; mergers; splits, and near-mergers; the regularity of sound change; functional effects on linguistic change.

Volume 2: Principles of Linguistic Change: Social Factors, 2001;

   the actuation problem; the social location of the innovators of change; change and the curvilinear pattern; the role of sex in linguistic change; the effect of ethnicity and race on change; the gravity model of diffusion; the social motivation of change.

Volume 3: Principles of Linguistic Change: Cognitive and Cultural Factors, 2010.

  the effect of change on comprehension across and within dialects; the acquisition and transmission of variable rules; principles of syntactic change and grammaticalization; the forms of variable rules and their place in the grammar.

http://www.ling.upenn.edu/~wlabov/home.html