This thesis is a quantitative study of sociolinguistic variation in the Vicholi (central) dialect of spoken Sindhi in Sindh, a south east province of Pakistan. Two speech communities are investigated, one urban and one rural. By an analysis of the speech of the urban area (Hyderabad) and the rural community (Old Hala) the thesis investigates linguistic change in both speech communities and effects a comparison of the two sets of changes. In the study major social transitional events are identified and it is argued that linguistic variation in the two speech communities is sensitive to such change. The study consists of seven chapters: Chapter one introduces the locale of research and discusses theoretical sociolinguistic concepts and issues of relevance to this study. Also included in this chapter is a socio-historical discussion of Sindh which serves as a background for the reader. Chapter two reviews the diachronic sociolinguistic situation in Sindh - particular emphsis is placed on the inception of Pakistan which is felt to have triggered linguistic variation in the two speech communities. Chapter three is an account of the research methodology. A brief discussion of linguistic change appears here, after which the sampling methods and the method of statistical analysis are discussed. Chapter four, five and six examine the results of the analysis of variation in the use of the three phonological variables - the diphthong, vowel and (r) variables - which have been correlated with the social parameters of age, education and sex. Chapter seven concludes the thesis with a brief summary of the findings.