  In many online communities, community leaders (i.e., moderators and
administrators) can proactively filter undesired content by requiring posts to
be approved before publication. But although many communities adopt post
approvals, there has been little research on its impact on community behavior.
Through a longitudinal analysis of 233,402 Facebook Groups, we examined 1) the
factors that led to a community adopting post approvals and 2) how the setting
shaped subsequent user activity and moderation in the group. We find that
communities that adopted post approvals tended to do so following sudden
increases in user activity (e.g., comments) and moderation (e.g., reported
posts). This adoption of post approvals led to fewer but higher-quality posts.
Though fewer posts were shared after adoption, not only did community members
write more comments, use more reactions, and spend more time on the posts that
were shared, they also reported these posts less. Further, post approvals did
not significantly increase the average time leaders spent in the group, though
groups that enabled the setting tended to appoint more leaders. Last, the
impact of post approvals varied with both group size and how the setting was
used, e.g.,, group size mediates whether leaders spent more or less time in the
group following the adoption of the setting. Our findings suggest ways that
proactive content moderation may be improved to better support online
communities.
