Recommendations for online system groups

A method comprising:

• maintaining a user account for each of a plurality of users of an online system;
• maintaining a plurality of groups in the online system, each group enabling the users of the online system to interact with other users who are members of the group;
• identifying a target user of the plurality of users to recommend to join one or more selected groups of the plurality of groups;
• selecting a plurality of groups as candidate groups for recommending to the target user, the selection of the plurality of groups based on a plurality of sourcing rules;
• for each of the candidate groups, computing a score for the candidate group for the target user by providing features extracted from the candidate group as input to a model generated based on machine learning, the score for the candidate group representing a likelihood of the target user joining the group if a recommendation to join the group is displayed to the target user;
• selecting one or more of the candidate groups for display to the viewing user, the selection of a candidate group based on the score for the candidate group;
• and
• sending a recommendation to join the selected groups for display to the target user.