Abstract: Educational research has described a social dimension to learning, and it is likely that technology complicates the social dimension of learning. This paper explores what differences, if any, are evident in the nature of Twitter #Edchat conversations, when taking into account Twitter’s technological features. Twitter contains a mashup of various features, such as indexing with hashtags and bringing conversational coherence by threading replies together. Following past Twitter studies, this work is framed by the affinity space concept, but expands this spatial understanding by looking at reply threads connected to a tweet containing a hashtag. In this study, more than one million #Edchat tweets were collected over a span of eight months, reply tweets were selected, and then additional “upstream” replies were collected as well. Differences between “hashtag replies” and “upstream replies” were measured by volume, content interactions, and social interactions.