Users make contributions to online communities in different ways. Prior literature has rarely investigated how different user groups make contributions to smoking cessation OHCs. To illuminate the contribution of different user groups in smoking cessation OHCs, this study aims to evaluate user contribution from two dimensions (Content-contribution and popularity) associated with users’ questioning and answering behaviors. Based on the user log data collected from a smoking cessation OHC in Finland (Stumppi.fi), we plan to assess user contribution level for four different user groups (lurker, conversation-starter, conversation-replier, and Conversation-starter & replier) based on user activity data via applying entropy method. The research might make theoretical contributions to the literature on user contribution and offer practical implications to smoking cessation OHC service providers.