<p>This study uses Incivility Spirals and Uses and Gratifications frameworks to explore how people discuss scientific topics on the social media site Reddit. Specifically, the goals of this project were to develop a new typology of online messages, examine how different factors influence online discourse, and determine whether uses and gratifications vary between Subreddits. The dataset consisted of comments on the top ten posts of 2019 from r/EverythingScience and r/Science. These Subreddits were examined because, although they both focus on science, they differ in terms of group rules and moderator style. Human coders and the text analysis software Linguistic Inquiry and Word Count were used to evaluate the comments on a series of dichotomous and continuous variables. These variables were used in a two-step cluster analysis to identify message typologies. Results indicate that there were three types of messages in the dataset: Polite Participation, Emotional Interrogation, and On Topic Information. Further analysis demonstrated that group norms and the first comment in a conversation impact the quality of discourse that takes place. Conversations on r/Science (the more strict Subreddit) that begin with an On Topic Information comment are more likely to be extremely deliberative, while conversation on r/EverythingScience that begin with an Emotional Interrogation comment are more likely to result in incivility spirals. Results also suggest differences in gratifications between Subreddits, with Redditors using r/Science for productive discussion and r/EverythingScience for heated debate. Theoretical and practical implications of these findings are discussed, along with avenues for future research. </p>