Posting comments on the news is one of the most popular forms of user participation in online newspapers, and there is great potential for public discourse that is associated with this form of user communication. However, this potential arises only when several users participate in commenting and when their communication becomes interactive. Based on an adaption of Galtung and Ruge’s theory of newsworthiness, we hypothesized that a news article’s news factors affect both participation levels and interactivity in a news item’s comments section. The data from an online content analysis of political news are consistent with the hypotheses. This article explores the ways in which news factors affect participation levels and interactivity, and it discusses the theoretical, normative, and practical implications of those findings.