This study attempts to characterize users' sociality in tagging by clustering factors that users consider when selecting tags for their bookmarks. Twenty-three frequent users of social bookmarking services were invited, and Q method and factor analysis have been applied in the study. Each cluster of users has varied focuses on personal, content, situational, and social factors when tagging. The study explores the four distinct types of sociality in tagging by the orientation of tag selection and the complexity of affecting factors. The results show different tendencies of sociality in tagging emerge, i.e., tag for me, us, all, and mixed. As there is the shift from functionality towards sociality for the social tagging applications, the initial findings may benefit the future related research.