This study examined the relationship between an individual learner's background, social network position, and interaction within a Massively Open Online Course (MOOC). Prior research has largely focused on the effects of background and social network position on quantitative features of interaction. This research considered qualitative features such as cognitive engagement level and sentiment polarity in interaction and the extent to which each of these factors influences interaction. We used a survey to collect demographic background information of MOOC users and then used social network analysis to examine the social network position of each MOOC user. We also used content analysis to evaluate the interaction on MOOC discussion forums. Background and social network positions were found to be associated with interaction differently within certain subgroups. The top and bottom 20% of learners who actively connected in social networks tended to engage in constructive cognitive activities, rather than active or interactive ones. The top 20% of threads showed a positive contribution of social network position diversity to interaction. Thread level diversity did not significantly impact the interaction level.