The purpose of the present paper was to adapt Gunuc and Kayri's (2010) "Internet Addiction Scale," with show validity and reliability for many various sampling groups, into the Azerbaijani language. Another objective of the study is to determine the prevalence of Internet addiction among Azerbaijani adolescents and youth, which preemptively requires adaptation of the "Internet Addiction Scale" into the Azerbaijani language. Samples in the study have been selected separately for both purposes (validity and prevalence). Data were collected from students attending Khazar University in Azerbaijan in 2014-2015, first, in order to conduct Confirmatory Factor Analysis of the scale and second, to determine the prevalence of Internet addiction among youth. Data was obtained from 309 students for the first purpose and from 836 students for the second one. Students in various majors within the research sample were stratified through stratified sampling and students in these majors were randomly selected. The four-factor structure of the scale was tested through CFA. The Cronbach's Alpha (a) internal consistency coefficient of the scale was calculated as a = 0.926. Reliability coefficient of 4 sub-factors, regarding the scale, was found as follows: a = 0.844 for "Withdrawal," a = 0.821 for "Controlling difficulty," a = 0.829 for "Disorder in Functionality" and a = 0.792 for "Social Isolation." The prevalence of Internet addiction among youth in Azerbaijan was determined. The study found that 51.9% were not Internet addicts, 40.6% were moderate Internet addicts, and 7.5% were Internet addicts. These findings show that the rate of Internet addicts, particularly in the categories of moderate Internet addicts and Internet addicts (48.1%), is not small enough to ignore.