Theories and Methodologies of Language Variation Studies

This paper begins with a brief reviewof major developments of language variation studies and its significance in linguis-tics.It then addresses three issues concerning theoretical constructs of language variation studies, namely, the lawful co-variation of social variations and language variations, the structure and system of language as orderly heterogeneity, and social functions of the language variation.Finally, the paper discusses issues of the research methodology in variation studies.