Aspects of the subject disclosure are directed towards increasing a community of interest group users of an interest group, e.g., a network site having a feed of posts generally related to a particular topic. Many newly created interest groups do not have enough content to keep users interested and attract new users. The technology described herein automatically obtains content that backfills such an interest group with additional related content. The backfilled content may be found by keywords search and/or by crawling general public data, data from specific sites, historical conversation data, and/or more widely scoped data. Also described is creating a new interest group and seeding the group with content based upon backfilling technology.