This research is entitled “The Value of Idiolect in Sociolinguistics Studies”; it is an attempt at introducing the concept, the scope and the limits of functions of idiolect in Sociolinguistics studies. The importance of the research lies in the fact that up to now no specified scientific work has been done about idiolect in Kurdish language, this despite the fact that it has mostly been dealt with wrongly. The research is divided into two chapters: the first chapter is dedicated to presenting the principles of Sociolinguistics as related to idiolect, as well as comparing it to sociolect and style, and showing their similarities and differences. As for the second chapter, it tackles in short the history of studies in individual language in the viewpoint of linguistic theories, and then the concept and definition of idiolect in Sociolinguistics have been depicted, later a detailed account of experts on idiolect in scientific studies have been presented, and in this regard two opposite directions appear; the first direction makes “individual talk” the center of the studies and hence explains and analyses the minute structures of “individual talk”, whereas the second direction, makes the individual talk the criterion and the basis of language analysis and through that it perceives the whole rules of group talk.