Loosely attached to other syntactic elements in an utterance, pragmatic markers (PM) are one of the most frequented pragmatic elements that fulfill various functions. Among a great number of PMs encountered in daily conversations, I think is one of the most prevalent PMs in native speaker and non-native speaker discourse. Thus, the purpose of this study was to unravel and compare the overall uses and functions of I think among Turkish learners of English and native speakers of British English. Adopting corpus-driven approach to explore the use of I think in both groups, the uses of the marker were classified depending on their functions that were designated through integrated reading of the data by using Wordsmith Tools 6.0. According to the results, the functions of I think were categorized under the domains of shield, booster, structural, evaluative and interactional. Log likelihood statistics was administrated to figure out whether the difference across the groups was statistical in their use of I think with regard to frequency and functional variety. The results revealed that there was not a statistical difference between the groups regarding the overall uses of the marker. However, differences in the functional distributions of I think across the groups were observed.