Online community managers work towards building and managing communities around a given brand or topic. Arisk imposed on such managers is that their community may die out and its utility diminish to users. Understanding what drives attention to content and the dynamics of discussions in a given community informs the community manager and/or host with the factors that are associated with attention, allowing them to detect a reduction in such factors. In this paper we gain insights into the idiosyncrasies that individual community forums exhibit in their attention patterns and how the factors that impact activity differ. We glean such insights through a two-stage approach that functions by (i) differentiating between seed posts - i.e. posts that solicit a reply - and non-seed posts - i.e. posts that did not get any replies, and (ii) predicting the level of attention that seed posts will generate. We explore the effectiveness of a range of features for predicting discussions and analyse their potential impact on discussion initiation and progress. Our findings show that the discussion behaviour of different communities exhibit interesting differences in terms of how attention is generated. Our results show amongst others that the purpose of a community as well as the specificity of the topic of a community impact which factors drive the reply behaviour of a community. For example, communities around very specific topics require posts to fit to the topical focus of the community in order to attract attention while communities around more general topics do not have this requirement. We also found that the factors which impact the start of discussions in communities often differ from the factors which impact the length of discussions.