For online news organizations trying to improve audience engagement strategies, Facebook Groups and Messenger chats constitute promising avenues. We explore whether these meso news-spaces, with different discourse architectures and group sizes, affect the substance of the discussion and people’s impressions. In this study, we experimentally tested how training and intimate forms of news engagement in small-group discussions on Facebook Messenger compare with larger conversations in a Facebook Group. The study draws from a real-world experiment in collaboration with Vox Media and its popular Facebook Group for the political podcast The Weeds. Results show that participants perceive the Messenger group as more civil and respectful and report being less prone to self-censor in the Messenger group. Comments in the Messenger group, however, are less relevant to The Weeds podcast and participation in the Messenger group leads people to have less favorable views of the large Facebook Group. The ways in which discourse architecture and group size affect digital discussions provide theoretical and practical insights.