5. A method comprising: storing a plurality of groups in a social networking system, each group including one or more users of the social networking system; determining a target user of the social networking system; accessing a user profile in the social networking system of the target user; identifying a set of social networking system users connected to the target user; identifying a set of candidate groups from the plurality of groups based on characteristics of the target user and characteristics of the social networking system users connected to the target user; determining, by one or more processors, a candidate score for each candidate group based on affinities between the users in the candidate group and the target user; selecting a group from the candidate groups based on the candidate scores; and presenting the selected group to the target user.
5. A method comprising: storing a plurality of groups in a social networking system, each group including one or more users of the social networking system; determining a target user of the social networking system; accessing a user profile in the social networking system of the target user; identifying a set of social networking system users connected to the target user; identifying a set of candidate groups from the plurality of groups based on characteristics of the target user and characteristics of the social networking system users connected to the target user; determining, by one or more processors, a candidate score for each candidate group based on affinities between the users in the candidate group and the target user; selecting a group from the candidate groups based on the candidate scores; and presenting the selected group to the target user. 15. The method of claim 5 , further comprising: adding the target user to the selected group.