Abstract: Research on online content diffusion is vast, but has rarely examined contextual factors, including the influence of online sharing mechanisms, such as social plugins (e.g., Facebook’s “Like” button), on online social networks (OSNs). While these mechanisms generally enable the content flow between senders and recipients, they vary in protecting users’ social and institutional privacy on OSNs. Additionally, sharing mechanisms might differ with respect to their labeling (e.g., positive vs. neutral), which might interact with the sharable content. We examined the effects of these three design aspects on users’ sharing behavior in a controlled experiment and two analyses of observational data. The results show that two types of sharing mechanisms negatively affect content sharing in the domain of news sharing: those that allow greater information flow control over the sharing process and thus protect users’ social privacy, and those that employ two-click designs in order to preserve users’ institutional privacy. These negative effects mainly stem from higher frictional costs associated with these features. For the average user in this domain, the disutility and additional cognitive effort generated by one additional click often mitigates the utility of sharing itself. Moreover, we find that neutral button labeling is important for fostering content sharing, as users might encounter schema incongruity when using a positively connoted label to share bad news. Overall, a wrong decision in terms of the sharing mechanism can easily decrease the number of shares by up to 86%. Therefore, content providers can easily and substantially increase content sharing by properly designing the sharing mechanism on their websites.