The psycholinguistic theory of Communication Accommodation proposes that people modify communication dynamics to minimize (or maximize) their social differences. Research on communication accommodation has shown that people who want social approval will modify their linguistic style to match that of their interactant; however, most studies have been conducted on small-scale datasets and in laboratory situations. In this work, we investigate the relationship between linguistic syntax usage and conversation participation in a more naturalistic conversational setting: social media conversations on Reddit.com. We introduce a novel approach for calculating document-level syntax similarity by relying on natural language processing methods and graph theory techniques. Using the proposed method, we present the results of two experiments which demonstrate that users who comment on a post tend to use syntax similar to that of the original post.