This chapter discusses the ambivalent nature of user comments. It provides an overview of current research on user comments in digital journalism and directions for future research. The chapter also discusses who reads and writes comments as well as motivations and inhibitors for doing so. It analyzes existing theory and research on the act of commenting, including thoughts and findings on commenting as an act of public deliberation and political action. The chapter also discusses prominent issues that come along with the bipolar nature of user comments, such as comment in/civility, comment moderation, and organizational perspectives and commenting policies, as well as commenting effects. Research suggests that the in/civility of comments can be explained by a variety of factors, including: story topic, sources, journalist participation in comment threads, journalist demography, and organizational commenting policies. The chapter concludes with directions for future research.